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Move most of MWCryptRand into libs

Browse source 
Dependency-inject the MW-specific parts of MWCryptRand via
MediaWikiServices into a generic CryptRand class that is in libs/.

Note that this removes the wfGetAllCallers() debug logging from
generate().

Change-Id: I9742735c266ee69fb247199d3c553cd2ad2a3987
This commit is contained in:
Kunal Mehta 2016-10-02 00:04:17 -07:00 committed by Aaron Schulz
parent 9300bc2933
commit 5bd6de67e3
6 changed files with 433 additions and 350 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
autoload.php
View file

@ -295,6 +295,7 @@ $wgAutoloadLocalClasses = [
'CreateAndPromote' => __DIR__ . '/maintenance/createAndPromote.php',
'CreateFileOp' => __DIR__ . '/includes/libs/filebackend/fileop/CreateFileOp.php',
'CreditsAction' => __DIR__ . '/includes/actions/CreditsAction.php',
'CryptRand' => __DIR__ . '/includes/libs/CryptRand.php',
'CssContent' => __DIR__ . '/includes/content/CssContent.php',
'CssContentHandler' => __DIR__ . '/includes/content/CssContentHandler.php',
'CsvStatsOutput' => __DIR__ . '/maintenance/language/StatOutputs.php',

9
includes/MediaWikiServices.php
View file

@ -3,6 +3,7 @@ namespace MediaWiki;
use Config;
use ConfigFactory;
use CryptRand;
use EventRelayerGroup;
use GenderCache;
use GlobalVarConfig;
@ -522,6 +523,14 @@ class MediaWikiServices extends ServiceContainer {
return $this->getService( 'WatchedItemQueryService' );
}
/**
* @since 1.28
* @return CryptRand
*/
public function getCryptRand() {
return $this->getService( 'CryptRand' );
}
/**
* @since 1.28
* @return MediaHandlerFactory

26
includes/ServiceWiring.php
View file

@ -39,6 +39,7 @@
use MediaWiki\Interwiki\ClassicInterwikiLookup;
use MediaWiki\Linker\LinkRendererFactory;
use MediaWiki\Logger\LoggerFactory;
use MediaWiki\MediaWikiServices;
return [
@ -158,6 +159,31 @@ return [
return new WatchedItemQueryService( $services->getDBLoadBalancer() );
},
'CryptRand' => function( MediaWikiServices $services ) {
$secretKey = $services->getMainConfig()->get( 'SecretKey' );
return new CryptRand(
[
// To try vary the system information of the state a bit more
// by including the system's hostname into the state
'wfHostname',
// It's mostly worthless but throw the wiki's id into the data
// for a little more variance
'wfWikiID',
// If we have a secret key set then throw it into the state as well
function() use ( $secretKey ) {
return $secretKey ?: '';
}
],
// The config file is likely the most often edited file we know should
// be around so include its stat info into the state.
// The constant with its location will almost always be defined, as
// WebStart.php defines MW_CONFIG_FILE to $IP/LocalSettings.php unless
// being configured with MW_CONFIG_CALLBACK (e.g. the installer).
defined( 'MW_CONFIG_FILE' ) ? [ MW_CONFIG_FILE ] : [],
LoggerFactory::getInstance( 'CryptRand' )
);
},
'MediaHandlerFactory' => function( MediaWikiServices $services ) {
return new MediaHandlerFactory(
$services->getMainConfig()->get( 'MediaHandlers' )

389
includes/libs/CryptRand.php Normal file
View file

@ -0,0 +1,389 @@
<?php
/**
* A cryptographic random generator class used for generating secret keys
*
* This is based in part on Drupal code as well as what we used in our own code
* prior to introduction of this class.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @author Daniel Friesen
* @file
*/
use Psr\Log\LoggerInterface;
class CryptRand {
/**
* Minimum number of iterations we want to make in our drift calculations.
*/
const MIN_ITERATIONS = 1000;
/**
* Number of milliseconds we want to spend generating each separate byte
* of the final generated bytes.
* This is used in combination with the hash length to determine the duration
* we should spend doing drift calculations.
*/
const MSEC_PER_BYTE = 0.5;
/**
* A boolean indicating whether the previous random generation was done using
* cryptographically strong random number generator or not.
*/
protected $strong = null;
/**
* List of functions to call to generate some random state
*
* @var callable[]
*/
protected $randomFuncs = [];
/**
* List of files to generate some random state from
*
* @var string[]
*/
protected $randomFiles = [];
/**
* @var LoggerInterface
*/
protected $logger;
public function __construct( array $randomFuncs, array $randomFiles, LoggerInterface $logger ) {
$this->randomFuncs = $randomFuncs;
$this->randomFiles = $randomFiles;
$this->logger = $logger;
}
/**
* Initialize an initial random state based off of whatever we can find
* @return string
*/
protected function initialRandomState() {
// $_SERVER contains a variety of unstable user and system specific information
// It'll vary a little with each page, and vary even more with separate users
// It'll also vary slightly across different machines
$state = serialize( $_SERVER );
// Try to gather a little entropy from the different php rand sources
$state .= rand() . uniqid( mt_rand(), true );
// Include some information about the filesystem's current state in the random state
$files = $this->randomFiles;
// We know this file is here so grab some info about ourselves
$files[] = __FILE__;
// We must also have a parent folder, and with the usual file structure, a grandparent
$files[] = __DIR__;
$files[] = dirname( __DIR__ );
foreach ( $files as $file ) {
MediaWiki\suppressWarnings();
$stat = stat( $file );
MediaWiki\restoreWarnings();
if ( $stat ) {
// stat() duplicates data into numeric and string keys so kill off all the numeric ones
foreach ( $stat as $k => $v ) {
if ( is_numeric( $k ) ) {
unset( $k );
}
}
// The absolute filename itself will differ from install to install so don't leave it out
$path = realpath( $file );
if ( $path !== false ) {
$state .= $path;
} else {
$state .= $file;
}
$state .= implode( '', $stat );
} else {
// The fact that the file isn't there is worth at least a
// minuscule amount of entropy.
$state .= '0';
}
}
// Try and make this a little more unstable by including the varying process
// id of the php process we are running inside of if we are able to access it
if ( function_exists( 'getmypid' ) ) {
$state .= getmypid();
}
// If available try to increase the instability of the data by throwing in
// the precise amount of memory that we happen to be using at the moment.
if ( function_exists( 'memory_get_usage' ) ) {
$state .= memory_get_usage( true );
}
foreach ( $this->randomFuncs as $randomFunc ) {
$state .= call_user_func( $randomFunc );
}
return $state;
}
/**
* Randomly hash data while mixing in clock drift data for randomness
*
* @param string $data The data to randomly hash.
* @return string The hashed bytes
* @author Tim Starling
*/
protected function driftHash( $data ) {
// Minimum number of iterations (to avoid slow operations causing the
// loop to gather little entropy)
$minIterations = self::MIN_ITERATIONS;
// Duration of time to spend doing calculations (in seconds)
$duration = ( self::MSEC_PER_BYTE / 1000 ) * MWCryptHash::hashLength();
// Create a buffer to use to trigger memory operations
$bufLength = 10000000;
$buffer = str_repeat( ' ', $bufLength );
$bufPos = 0;
// Iterate for $duration seconds or at least $minIterations number of iterations
$iterations = 0;
$startTime = microtime( true );
$currentTime = $startTime;
while ( $iterations < $minIterations || $currentTime - $startTime < $duration ) {
// Trigger some memory writing to trigger some bus activity
// This may create variance in the time between iterations
$bufPos = ( $bufPos + 13 ) % $bufLength;
$buffer[$bufPos] = ' ';
// Add the drift between this iteration and the last in as entropy
$nextTime = microtime( true );
$delta = (int)( ( $nextTime - $currentTime ) * 1000000 );
$data .= $delta;
// Every 100 iterations hash the data and entropy
if ( $iterations % 100 === 0 ) {
$data = sha1( $data );
}
$currentTime = $nextTime;
$iterations++;
}
$timeTaken = $currentTime - $startTime;
$data = MWCryptHash::hash( $data );
$this->logger->debug( "Clock drift calculation " .
"(time-taken=" . ( $timeTaken * 1000 ) . "ms, " .
"iterations=$iterations, " .
"time-per-iteration=" . ( $timeTaken / $iterations * 1e6 ) . "us)\n" );
return $data;
}
/**
* Return a rolling random state initially build using data from unstable sources
* @return string A new weak random state
*/
protected function randomState() {
static $state = null;
if ( is_null( $state ) ) {
// Initialize the state with whatever unstable data we can find
// It's important that this data is hashed right afterwards to prevent
// it from being leaked into the output stream
$state = MWCryptHash::hash( $this->initialRandomState() );
}
// Generate a new random state based on the initial random state or previous
// random state by combining it with clock drift
$state = $this->driftHash( $state );
return $state;
}
/**
* Return a boolean indicating whether or not the source used for cryptographic
* random bytes generation in the previously run generate* call
* was cryptographically strong.
*
* @return bool Returns true if the source was strong, false if not.
*/
public function wasStrong() {
if ( is_null( $this->strong ) ) {
throw new RuntimeException( __METHOD__ . ' called before generation of random data' );
}
return $this->strong;
}
/**
* Generate a run of (ideally) cryptographically random data and return
* it in raw binary form.
* You can use CryptRand::wasStrong() if you wish to know if the source used
* was cryptographically strong.
*
* @param int $bytes The number of bytes of random data to generate
* @param bool $forceStrong Pass true if you want generate to prefer cryptographically
* strong sources of entropy even if reading from them may steal
* more entropy from the system than optimal.
* @return string Raw binary random data
*/
public function generate( $bytes, $forceStrong = false ) {
$this->logger->debug( "Generating cryptographic random bytes for\n" );
$bytes = floor( $bytes );
static $buffer = '';
if ( is_null( $this->strong ) ) {
// Set strength to false initially until we know what source data is coming from
$this->strong = true;
}
if ( strlen( $buffer ) < $bytes ) {
// If available make use of mcrypt_create_iv URANDOM source to generate randomness
// On unix-like systems this reads from /dev/urandom but does it without any buffering
// and bypasses openbasedir restrictions, so it's preferable to reading directly
// On Windows starting in PHP 5.3.0 Windows' native CryptGenRandom is used to generate
// entropy so this is also preferable to just trying to read urandom because it may work
// on Windows systems as well.
if ( function_exists( 'mcrypt_create_iv' ) ) {
$rem = $bytes - strlen( $buffer );
$iv = mcrypt_create_iv( $rem, MCRYPT_DEV_URANDOM );
if ( $iv === false ) {
$this->logger->debug( "mcrypt_create_iv returned false.\n" );
} else {
$buffer .= $iv;
$this->logger->debug( "mcrypt_create_iv generated " . strlen( $iv ) .
" bytes of randomness.\n" );
}
}
}
if ( strlen( $buffer ) < $bytes ) {
if ( function_exists( 'openssl_random_pseudo_bytes' ) ) {
$rem = $bytes - strlen( $buffer );
$openssl_bytes = openssl_random_pseudo_bytes( $rem, $openssl_strong );
if ( $openssl_bytes === false ) {
$this->logger->debug( "openssl_random_pseudo_bytes returned false.\n" );
} else {
$buffer .= $openssl_bytes;
$this->logger->debug( "openssl_random_pseudo_bytes generated " .
strlen( $openssl_bytes ) . " bytes of " .
( $openssl_strong ? "strong" : "weak" ) . " randomness.\n" );
}
if ( strlen( $buffer ) >= $bytes ) {
// openssl tells us if the random source was strong, if some of our data was generated
// using it use it's say on whether the randomness is strong
$this->strong = !!$openssl_strong;
}
}
}
// Only read from urandom if we can control the buffer size or were passed forceStrong
if ( strlen( $buffer ) < $bytes &&
( function_exists( 'stream_set_read_buffer' ) || $forceStrong )
) {
$rem = $bytes - strlen( $buffer );
if ( !function_exists( 'stream_set_read_buffer' ) && $forceStrong ) {
$this->logger->debug( "Was forced to read from /dev/urandom " .
"without control over the buffer size.\n" );
}
// /dev/urandom is generally considered the best possible commonly
// available random source, and is available on most *nix systems.
MediaWiki\suppressWarnings();
$urandom = fopen( "/dev/urandom", "rb" );
MediaWiki\restoreWarnings();
// Attempt to read all our random data from urandom
// php's fread always does buffered reads based on the stream's chunk_size
// so in reality it will usually read more than the amount of data we're
// asked for and not storing that risks depleting the system's random pool.
// If stream_set_read_buffer is available set the chunk_size to the amount
// of data we need. Otherwise read 8k, php's default chunk_size.
if ( $urandom ) {
// php's default chunk_size is 8k
$chunk_size = 1024 * 8;
if ( function_exists( 'stream_set_read_buffer' ) ) {
// If possible set the chunk_size to the amount of data we need
stream_set_read_buffer( $urandom, $rem );
$chunk_size = $rem;
}
$random_bytes = fread( $urandom, max( $chunk_size, $rem ) );
$buffer .= $random_bytes;
fclose( $urandom );
$this->logger->debug( "/dev/urandom generated " . strlen( $random_bytes ) .
" bytes of randomness.\n" );
if ( strlen( $buffer ) >= $bytes ) {
// urandom is always strong, set to true if all our data was generated using it
$this->strong = true;
}
} else {
$this->logger->debug( "/dev/urandom could not be opened.\n" );
}
}
// If we cannot use or generate enough data from a secure source
// use this loop to generate a good set of pseudo random data.
// This works by initializing a random state using a pile of unstable data
// and continually shoving it through a hash along with a variable salt.
// We hash the random state with more salt to avoid the state from leaking
// out and being used to predict the /randomness/ that follows.
if ( strlen( $buffer ) < $bytes ) {
$this->logger->debug( __METHOD__ .
": Falling back to using a pseudo random state to generate randomness.\n" );
}
while ( strlen( $buffer ) < $bytes ) {
$buffer .= MWCryptHash::hmac( $this->randomState(), strval( mt_rand() ) );
// This code is never really cryptographically strong, if we use it
// at all, then set strong to false.
$this->strong = false;
}
// Once the buffer has been filled up with enough random data to fulfill
// the request shift off enough data to handle the request and leave the
// unused portion left inside the buffer for the next request for random data
$generated = substr( $buffer, 0, $bytes );
$buffer = substr( $buffer, $bytes );
$this->logger->debug( strlen( $buffer ) .
" bytes of randomness leftover in the buffer.\n" );
return $generated;
}
/**
* Generate a run of (ideally) cryptographically random data and return
* it in hexadecimal string format.
* You can use CryptRand::wasStrong() if you wish to know if the source used
* was cryptographically strong.
*
* @param int $chars The number of hex chars of random data to generate
* @param bool $forceStrong Pass true if you want generate to prefer cryptographically
* strong sources of entropy even if reading from them may steal
* more entropy from the system than optimal.
* @return string Hexadecimal random data
*/
public function generateHex( $chars, $forceStrong = false ) {
// hex strings are 2x the length of raw binary so we divide the length in half
// odd numbers will result in a .5 that leads the generate() being 1 character
// short, so we use ceil() to ensure that we always have enough bytes
$bytes = ceil( $chars / 2 );
// Generate the data and then convert it to a hex string
$hex = bin2hex( $this->generate( $bytes, $forceStrong ) );
// A bit of paranoia here, the caller asked for a specific length of string
// here, and it's possible (eg when given an odd number) that we may actually
// have at least 1 char more than they asked for. Just in case they made this
// call intending to insert it into a database that does truncation we don't
// want to give them too much and end up with their database and their live
// code having two different values because part of what we gave them is truncated
// hence, we strip out any run of characters longer than what we were asked for.
return substr( $hex, 0, $chars );
}
}

357
includes/utils/MWCryptRand.php
View file

@ -24,357 +24,14 @@
* @file
*/
use MediaWiki\MediaWikiServices;
class MWCryptRand {
/**
* Minimum number of iterations we want to make in our drift calculations.
*/
const MIN_ITERATIONS = 1000;
/**
* Number of milliseconds we want to spend generating each separate byte
* of the final generated bytes.
* This is used in combination with the hash length to determine the duration
* we should spend doing drift calculations.
*/
const MSEC_PER_BYTE = 0.5;
/**
* Singleton instance for public use
*/
protected static $singleton = null;
/**
* A boolean indicating whether the previous random generation was done using
* cryptographically strong random number generator or not.
*/
protected $strong = null;
/**
* Initialize an initial random state based off of whatever we can find
* @return string
*/
protected function initialRandomState() {
// $_SERVER contains a variety of unstable user and system specific information
// It'll vary a little with each page, and vary even more with separate users
// It'll also vary slightly across different machines
$state = serialize( $_SERVER );
// To try vary the system information of the state a bit more
// by including the system's hostname into the state
$state .= wfHostname();
// Try to gather a little entropy from the different php rand sources
$state .= rand() . uniqid( mt_rand(), true );
// Include some information about the filesystem's current state in the random state
$files = [];
// We know this file is here so grab some info about ourselves
$files[] = __FILE__;
// We must also have a parent folder, and with the usual file structure, a grandparent
$files[] = __DIR__;
$files[] = dirname( __DIR__ );
// The config file is likely the most often edited file we know should
// be around so include its stat info into the state.
// The constant with its location will almost always be defined, as
// WebStart.php defines MW_CONFIG_FILE to $IP/LocalSettings.php unless
// being configured with MW_CONFIG_CALLBACK (e.g. the installer).
if ( defined( 'MW_CONFIG_FILE' ) ) {
$files[] = MW_CONFIG_FILE;
}
foreach ( $files as $file ) {
MediaWiki\suppressWarnings();
$stat = stat( $file );
MediaWiki\restoreWarnings();
if ( $stat ) {
// stat() duplicates data into numeric and string keys so kill off all the numeric ones
foreach ( $stat as $k => $v ) {
if ( is_numeric( $k ) ) {
unset( $k );
}
}
// The absolute filename itself will differ from install to install so don't leave it out
$path = realpath( $file );
if ( $path !== false ) {
$state .= $path;
} else {
$state .= $file;
}
$state .= implode( '', $stat );
} else {
// The fact that the file isn't there is worth at least a
// minuscule amount of entropy.
$state .= '0';
}
}
// Try and make this a little more unstable by including the varying process
// id of the php process we are running inside of if we are able to access it
if ( function_exists( 'getmypid' ) ) {
$state .= getmypid();
}
// If available try to increase the instability of the data by throwing in
// the precise amount of memory that we happen to be using at the moment.
if ( function_exists( 'memory_get_usage' ) ) {
$state .= memory_get_usage( true );
}
// It's mostly worthless but throw the wiki's id into the data for a little more variance
$state .= wfWikiID();
// If we have a secret key set then throw it into the state as well
global $wgSecretKey;
if ( $wgSecretKey ) {
$state .= $wgSecretKey;
}
return $state;
}
/**
* Randomly hash data while mixing in clock drift data for randomness
*
* @param string $data The data to randomly hash.
* @return string The hashed bytes
* @author Tim Starling
*/
protected function driftHash( $data ) {
// Minimum number of iterations (to avoid slow operations causing the
// loop to gather little entropy)
$minIterations = self::MIN_ITERATIONS;
// Duration of time to spend doing calculations (in seconds)
$duration = ( self::MSEC_PER_BYTE / 1000 ) * MWCryptHash::hashLength();
// Create a buffer to use to trigger memory operations
$bufLength = 10000000;
$buffer = str_repeat( ' ', $bufLength );
$bufPos = 0;
// Iterate for $duration seconds or at least $minIterations number of iterations
$iterations = 0;
$startTime = microtime( true );
$currentTime = $startTime;
while ( $iterations < $minIterations || $currentTime - $startTime < $duration ) {
// Trigger some memory writing to trigger some bus activity
// This may create variance in the time between iterations
$bufPos = ( $bufPos + 13 ) % $bufLength;
$buffer[$bufPos] = ' ';
// Add the drift between this iteration and the last in as entropy
$nextTime = microtime( true );
$delta = (int)( ( $nextTime - $currentTime ) * 1000000 );
$data .= $delta;
// Every 100 iterations hash the data and entropy
if ( $iterations % 100 === 0 ) {
$data = sha1( $data );
}
$currentTime = $nextTime;
$iterations++;
}
$timeTaken = $currentTime - $startTime;
$data = MWCryptHash::hash( $data );
wfDebug( __METHOD__ . ": Clock drift calculation " .
"(time-taken=" . ( $timeTaken * 1000 ) . "ms, " .
"iterations=$iterations, " .
"time-per-iteration=" . ( $timeTaken / $iterations * 1e6 ) . "us)\n" );
return $data;
}
/**
* Return a rolling random state initially build using data from unstable sources
* @return string A new weak random state
*/
protected function randomState() {
static $state = null;
if ( is_null( $state ) ) {
// Initialize the state with whatever unstable data we can find
// It's important that this data is hashed right afterwards to prevent
// it from being leaked into the output stream
$state = MWCryptHash::hash( $this->initialRandomState() );
}
// Generate a new random state based on the initial random state or previous
// random state by combining it with clock drift
$state = $this->driftHash( $state );
return $state;
}
/**
* @see self::wasStrong()
*/
public function realWasStrong() {
if ( is_null( $this->strong ) ) {
throw new MWException( __METHOD__ . ' called before generation of random data' );
}
return $this->strong;
}
/**
* @see self::generate()
*/
public function realGenerate( $bytes, $forceStrong = false ) {
wfDebug( __METHOD__ . ": Generating cryptographic random bytes for " .
wfGetAllCallers( 5 ) . "\n" );
$bytes = floor( $bytes );
static $buffer = '';
if ( is_null( $this->strong ) ) {
// Set strength to false initially until we know what source data is coming from
$this->strong = true;
}
if ( strlen( $buffer ) < $bytes ) {
// If available make use of mcrypt_create_iv URANDOM source to generate randomness
// On unix-like systems this reads from /dev/urandom but does it without any buffering
// and bypasses openbasedir restrictions, so it's preferable to reading directly
// On Windows starting in PHP 5.3.0 Windows' native CryptGenRandom is used to generate
// entropy so this is also preferable to just trying to read urandom because it may work
// on Windows systems as well.
if ( function_exists( 'mcrypt_create_iv' ) ) {
$rem = $bytes - strlen( $buffer );
$iv = mcrypt_create_iv( $rem, MCRYPT_DEV_URANDOM );
if ( $iv === false ) {
wfDebug( __METHOD__ . ": mcrypt_create_iv returned false.\n" );
} else {
$buffer .= $iv;
wfDebug( __METHOD__ . ": mcrypt_create_iv generated " . strlen( $iv ) .
" bytes of randomness.\n" );
}
}
}
if ( strlen( $buffer ) < $bytes ) {
if ( function_exists( 'openssl_random_pseudo_bytes' ) ) {
$rem = $bytes - strlen( $buffer );
$openssl_bytes = openssl_random_pseudo_bytes( $rem, $openssl_strong );
if ( $openssl_bytes === false ) {
wfDebug( __METHOD__ . ": openssl_random_pseudo_bytes returned false.\n" );
} else {
$buffer .= $openssl_bytes;
wfDebug( __METHOD__ . ": openssl_random_pseudo_bytes generated " .
strlen( $openssl_bytes ) . " bytes of " .
( $openssl_strong ? "strong" : "weak" ) . " randomness.\n" );
}
if ( strlen( $buffer ) >= $bytes ) {
// openssl tells us if the random source was strong, if some of our data was generated
// using it use it's say on whether the randomness is strong
$this->strong = !!$openssl_strong;
}
}
}
// Only read from urandom if we can control the buffer size or were passed forceStrong
if ( strlen( $buffer ) < $bytes &&
( function_exists( 'stream_set_read_buffer' ) || $forceStrong )
) {
$rem = $bytes - strlen( $buffer );
if ( !function_exists( 'stream_set_read_buffer' ) && $forceStrong ) {
wfDebug( __METHOD__ . ": Was forced to read from /dev/urandom " .
"without control over the buffer size.\n" );
}
// /dev/urandom is generally considered the best possible commonly
// available random source, and is available on most *nix systems.
MediaWiki\suppressWarnings();
$urandom = fopen( "/dev/urandom", "rb" );
MediaWiki\restoreWarnings();
// Attempt to read all our random data from urandom
// php's fread always does buffered reads based on the stream's chunk_size
// so in reality it will usually read more than the amount of data we're
// asked for and not storing that risks depleting the system's random pool.
// If stream_set_read_buffer is available set the chunk_size to the amount
// of data we need. Otherwise read 8k, php's default chunk_size.
if ( $urandom ) {
// php's default chunk_size is 8k
$chunk_size = 1024 * 8;
if ( function_exists( 'stream_set_read_buffer' ) ) {
// If possible set the chunk_size to the amount of data we need
stream_set_read_buffer( $urandom, $rem );
$chunk_size = $rem;
}
$random_bytes = fread( $urandom, max( $chunk_size, $rem ) );
$buffer .= $random_bytes;
fclose( $urandom );
wfDebug( __METHOD__ . ": /dev/urandom generated " . strlen( $random_bytes ) .
" bytes of randomness.\n" );
if ( strlen( $buffer ) >= $bytes ) {
// urandom is always strong, set to true if all our data was generated using it
$this->strong = true;
}
} else {
wfDebug( __METHOD__ . ": /dev/urandom could not be opened.\n" );
}
}
// If we cannot use or generate enough data from a secure source
// use this loop to generate a good set of pseudo random data.
// This works by initializing a random state using a pile of unstable data
// and continually shoving it through a hash along with a variable salt.
// We hash the random state with more salt to avoid the state from leaking
// out and being used to predict the /randomness/ that follows.
if ( strlen( $buffer ) < $bytes ) {
wfDebug( __METHOD__ .
": Falling back to using a pseudo random state to generate randomness.\n" );
}
while ( strlen( $buffer ) < $bytes ) {
$buffer .= MWCryptHash::hmac( $this->randomState(), strval( mt_rand() ) );
// This code is never really cryptographically strong, if we use it
// at all, then set strong to false.
$this->strong = false;
}
// Once the buffer has been filled up with enough random data to fulfill
// the request shift off enough data to handle the request and leave the
// unused portion left inside the buffer for the next request for random data
$generated = substr( $buffer, 0, $bytes );
$buffer = substr( $buffer, $bytes );
wfDebug( __METHOD__ . ": " . strlen( $buffer ) .
" bytes of randomness leftover in the buffer.\n" );
return $generated;
}
/**
* @see self::generateHex()
*/
public function realGenerateHex( $chars, $forceStrong = false ) {
// hex strings are 2x the length of raw binary so we divide the length in half
// odd numbers will result in a .5 that leads the generate() being 1 character
// short, so we use ceil() to ensure that we always have enough bytes
$bytes = ceil( $chars / 2 );
// Generate the data and then convert it to a hex string
$hex = bin2hex( $this->generate( $bytes, $forceStrong ) );
// A bit of paranoia here, the caller asked for a specific length of string
// here, and it's possible (eg when given an odd number) that we may actually
// have at least 1 char more than they asked for. Just in case they made this
// call intending to insert it into a database that does truncation we don't
// want to give them too much and end up with their database and their live
// code having two different values because part of what we gave them is truncated
// hence, we strip out any run of characters longer than what we were asked for.
return substr( $hex, 0, $chars );
}
/** Publicly exposed static methods **/
/**
* Return a singleton instance of MWCryptRand
* @return MWCryptRand
* @return CryptRand
*/
protected static function singleton() {
if ( is_null( self::$singleton ) ) {
self::$singleton = new self;
}
return self::$singleton;
return MediaWikiServices::getInstance()->getCryptRand();
}
/**
@ -385,7 +42,7 @@ class MWCryptRand {
* @return bool Returns true if the source was strong, false if not.
*/
public static function wasStrong() {
return self::singleton()->realWasStrong();
return self::singleton()->wasStrong();
}
/**
@ -401,7 +58,7 @@ class MWCryptRand {
* @return string Raw binary random data
*/
public static function generate( $bytes, $forceStrong = false ) {
return self::singleton()->realGenerate( $bytes, $forceStrong );
return self::singleton()->generate( $bytes, $forceStrong );
}
/**
@ -417,6 +74,6 @@ class MWCryptRand {
* @return string Hexadecimal random data
*/
public static function generateHex( $chars, $forceStrong = false ) {
return self::singleton()->realGenerateHex( $chars, $forceStrong );
return self::singleton()->generateHex( $chars, $forceStrong );
}
}

1
tests/phpunit/includes/MediaWikiServicesTest.php
View file

@ -312,6 +312,7 @@ class MediaWikiServicesTest extends MediaWikiTestCase {
'DBLoadBalancer' => [ 'DBLoadBalancer', 'LoadBalancer' ],
'WatchedItemStore' => [ 'WatchedItemStore', WatchedItemStore::class ],
'WatchedItemQueryService' => [ 'WatchedItemQueryService', WatchedItemQueryService::class ],
'CryptRand' => [ 'CryptRand', CryptRand::class ],
'MediaHandlerFactory' => [ 'MediaHandlerFactory', MediaHandlerFactory::class ],
'GenderCache' => [ 'GenderCache', GenderCache::class ],
'LinkCache' => [ 'LinkCache', LinkCache::class ],