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chore: Déplacer dans le plugin safehtml la lib et la fonction de sanitization des SVG

Refs: #4787\#issuecomment-41625
remotes/checkIfPRContentChanged-1663682096555464572/issue_4786
Cerdic 5 months ago
parent
commit
190c63ee31
  1. 340
      lib/svg-sanitizer/LICENSE
  2. 92
      lib/svg-sanitizer/README.md
  3. 33
      lib/svg-sanitizer/composer.json
  4. 169
      lib/svg-sanitizer/src/ElementReference/Resolver.php
  5. 153
      lib/svg-sanitizer/src/ElementReference/Subject.php
  6. 49
      lib/svg-sanitizer/src/ElementReference/Usage.php
  7. 39
      lib/svg-sanitizer/src/Exceptions/NestingException.php
  8. 53
      lib/svg-sanitizer/src/Helper.php
  9. 630
      lib/svg-sanitizer/src/Sanitizer.php
  10. 357
      lib/svg-sanitizer/src/data/AllowedAttributes.php
  11. 245
      lib/svg-sanitizer/src/data/AllowedTags.php
  12. 19
      lib/svg-sanitizer/src/data/AttributeInterface.php
  13. 19
      lib/svg-sanitizer/src/data/TagInterface.php
  14. 64
      lib/svg-sanitizer/src/data/XPath.php
  15. 192
      lib/svg-sanitizer/src/svg-scanner.php
  16. 117
      sanitizer/svg.php

340
lib/svg-sanitizer/LICENSE

@ -0,0 +1,340 @@
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92
lib/svg-sanitizer/README.md

@ -0,0 +1,92 @@
# svg-sanitizer
[![Build Status](https://travis-ci.org/darylldoyle/svg-sanitizer.svg?branch=master)](https://travis-ci.org/darylldoyle/svg-sanitizer) [![Test Coverage](https://codeclimate.com/github/darylldoyle/svg-sanitizer/badges/coverage.svg)](https://codeclimate.com/github/darylldoyle/svg-sanitizer/coverage)
This is my attempt at building a decent SVG sanitizer in PHP. The work is laregely borrowed from [DOMPurify](https://github.com/cure53/DOMPurify).
## Installation
Either require `enshrined/svg-sanitize` through composer or download the repo and include the old way!
## Usage
Using this is fairly easy. Create a new instance of `enshrined\svgSanitize\Sanitizer` and then call the `sanitize` whilst passing in your dirty SVG/XML
**Basic Example**
```php
use enshrined\svgSanitize\Sanitizer;
// Create a new sanitizer instance
$sanitizer = new Sanitizer();
// Load the dirty svg
$dirtySVG = file_get_contents('filthy.svg');
// Pass it to the sanitizer and get it back clean
$cleanSVG = $sanitizer->sanitize($dirtySVG);
// Now do what you want with your clean SVG/XML data
```
## Output
This will either return a sanitized SVG/XML string or boolean `false` if XML parsing failed (usually due to a badly formatted file).
## Options
You may pass your own whitelist of tags and attributes by using the `Sanitizer::setAllowedTags` and `Sanitizer::setAllowedAttrs` methods respectively.
These methods require that you implement the `enshrined\svgSanitize\data\TagInterface` or `enshrined\svgSanitize\data\AttributeInterface`.
## Remove remote references
You have the option to remove attributes that reference remote files, this will stop HTTP leaks but will add an overhead to the sanitizer.
This defaults to false, set to true to remove references.
`$sanitizer->removeRemoteReferences(true);`
## Viewing Sanitization Issues
You may use the `getXmlIssues()` method to return an array of issues that occurred during sanitization.
This may be useful for logging or providing feedback to the user on why an SVG was refused.
`$issues = $sanitizer->getXmlIssues();`
## Minification
You can minify the XML output by calling `$sanitizer->minify(true);`.
## Demo
There is a demo available at: [http://svg.enshrined.co.uk/](http://svg.enshrined.co.uk/)
## WordPress
I've just released a WordPress plugin containing this code so you can sanitize your WordPress uploads. It's available from the WordPress plugin directory: [https://wordpress.org/plugins/safe-svg/](https://wordpress.org/plugins/safe-svg/)
## Drupal
[Michael Potter](https://github.com/heyMP) has kindly created a Drupal module for this library which is available at: [https://www.drupal.org/project/svg_sanitizer](https://www.drupal.org/project/svg_sanitizer)
## TYPO3
An integration for TYPO3 CMS of this library is available as composer package `t3g/svg-sanitizer` at [https://github.com/TYPO3GmbH/svg_sanitizer](https://github.com/TYPO3GmbH/svg_sanitizer)
## Tests
You can run these by running `vendor/bin/phpunit` from the base directory of this package.
## Standalone scanning of files via CLI
Thanks to the work by [gudmdharalds](https://github.com/gudmdharalds) there's now a standalone scanner that can be used via the CLI.
Any errors will be output in JSON format. See [the PR](https://github.com/darylldoyle/svg-sanitizer/pull/25) for an example.
Use it as follows: `php svg-scanner.php ~/svgs/myfile.svg`
## To-Do
More extensive testing for the SVGs/XML would be lovely, I'll try and add these soon. If you feel like doing it for me, please do and make a PR!

33
lib/svg-sanitizer/composer.json

@ -0,0 +1,33 @@
{
"name": "enshrined/svg-sanitize",
"description": "An SVG sanitizer for PHP",
"license": "GPL-2.0-or-later",
"authors": [
{
"name": "Daryll Doyle",
"email": "daryll@enshrined.co.uk"
}
],
"scripts": {
"test": "phpunit --no-coverage"
},
"autoload": {
"psr-4": {
"enshrined\\svgSanitize\\": "src"
}
},
"autoload-dev": {
"psr-4": {
"enshrined\\svgSanitize\\Tests\\": "tests"
}
},
"require": {
"ext-dom": "*",
"ext-libxml": "*",
"php": "^7.0 || ^8.0"
},
"require-dev": {
"phpunit/phpunit": "^6.5 || ^8.5",
"codeclimate/php-test-reporter": "^0.1.2"
}
}

169
lib/svg-sanitizer/src/ElementReference/Resolver.php

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<?php
namespace enshrined\svgSanitize\ElementReference;
use enshrined\svgSanitize\data\XPath;
use enshrined\svgSanitize\Exceptions\NestingException;
use enshrined\svgSanitize\Helper;
class Resolver
{
/**
* @var XPath
*/
protected $xPath;
/**
* @var Subject[]
*/
protected $subjects = [];
/**
* @var array DOMElement[]
*/
protected $elementsToRemove = [];
/**
* @var int
*/
protected $useNestingLimit;
public function __construct(XPath $xPath, $useNestingLimit)
{
$this->xPath = $xPath;
$this->useNestingLimit = $useNestingLimit;
}
public function collect()
{
$this->collectIdentifiedElements();
$this->processReferences();
$this->determineInvalidSubjects();
}
/**
* Resolves one subject by element.
*
* @param \DOMElement $element
* @param bool $considerChildren Whether to search in Subject's children as well
* @return Subject|null
*/
public function findByElement(\DOMElement $element, $considerChildren = false)
{
foreach ($this->subjects as $subject) {
if (
$element === $subject->getElement()
|| $considerChildren && Helper::isElementContainedIn($element, $subject->getElement())
) {
return $subject;
}
}
return null;
}
/**
* Resolves subjects (plural!) by element id - in theory malformed
* DOM might have same ids assigned to different elements and leaving
* it to client/browser implementation which element to actually use.
*
* @param string $elementId
* @return Subject[]
*/
public function findByElementId($elementId)
{
return array_filter(
$this->subjects,
function (Subject $subject) use ($elementId) {
return $elementId === $subject->getElementId();
}
);
}
/**
* Collects elements having `id` attribute (those that can be referenced).
*/
protected function collectIdentifiedElements()
{
/** @var \DOMNodeList|\DOMElement[] $elements */
$elements = $this->xPath->query('//*[@id]');
foreach ($elements as $element) {
$this->subjects[$element->getAttribute('id')] = new Subject($element, $this->useNestingLimit);
}
}
/**
* Processes references from and to elements having `id` attribute concerning
* their occurrence in `<use ... xlink:href="#identifier">` statements.
*/
protected function processReferences()
{
$useNodeName = $this->xPath->createNodeName('use');
foreach ($this->subjects as $subject) {
$useElements = $this->xPath->query(
$useNodeName . '[@href or @xlink:href]',
$subject->getElement()
);
/** @var \DOMElement $useElement */
foreach ($useElements as $useElement) {
$useId = Helper::extractIdReferenceFromHref(
Helper::getElementHref($useElement)
);
if ($useId === null || !isset($this->subjects[$useId])) {
continue;
}
$subject->addUse($this->subjects[$useId]);
$this->subjects[$useId]->addUsedIn($subject);
}
}
}
/**
* Determines and tags infinite loops.
*/
protected function determineInvalidSubjects()
{
foreach ($this->subjects as $subject) {
if (in_array($subject->getElement(), $this->elementsToRemove)) {
continue;
}
$useId = Helper::extractIdReferenceFromHref(
Helper::getElementHref($subject->getElement())
);
try {
if ($useId === $subject->getElementId()) {
$this->markSubjectAsInvalid($subject);
} elseif ($subject->hasInfiniteLoop()) {
$this->markSubjectAsInvalid($subject);
}
} catch (NestingException $e) {
$this->elementsToRemove[] = $e->getElement();
$this->markSubjectAsInvalid($subject);
}
}
}
/**
* Get all the elements that caused a nesting exception.
*
* @return array
*/
public function getElementsToRemove() {
return $this->elementsToRemove;
}
/**
* The Subject is invalid for some reason, therefore we should
* remove it and all it's child usages.
*
* @param Subject $subject
*/
protected function markSubjectAsInvalid(Subject $subject) {
$this->elementsToRemove = array_merge(
$this->elementsToRemove,
$subject->clearInternalAndGetAffectedElements()
);
}
}

153
lib/svg-sanitizer/src/ElementReference/Subject.php

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<?php
namespace enshrined\svgSanitize\ElementReference;
class Subject
{
/**
* @var \DOMElement
*/
protected $element;
/**
* @var Usage[]
*/
protected $useCollection = [];
/**
* @var Usage[]
*/
protected $usedInCollection = [];
/**
* @var int
*/
protected $useNestingLimit;
/**
* Subject constructor.
*
* @param \DOMElement $element
* @param int $useNestingLimit
*/
public function __construct(\DOMElement $element, $useNestingLimit)
{
$this->element = $element;
$this->useNestingLimit = $useNestingLimit;
}
/**
* @return \DOMElement
*/
public function getElement()
{
return $this->element;
}
/**
* @return string
*/
public function getElementId()
{
return $this->element->getAttribute('id');
}
/**
* @param array $subjects Previously processed subjects
* @param int $level The current level of nesting.
* @return bool
* @throws \enshrined\svgSanitize\Exceptions\NestingException
*/
public function hasInfiniteLoop(array $subjects = [], $level = 1)
{
if ($level > $this->useNestingLimit) {
throw new \enshrined\svgSanitize\Exceptions\NestingException('Nesting level too high, aborting', 1570713498, null, $this->getElement());
}
if (in_array($this, $subjects, true)) {
return true;
}
$subjects[] = $this;
foreach ($this->useCollection as $usage) {
if ($usage->getSubject()->hasInfiniteLoop($subjects, $level + 1)) {
return true;
}
}
return false;
}
/**
* @param Subject $subject
*/
public function addUse(Subject $subject)
{
if ($subject === $this) {
throw new \LogicException('Cannot add self usage', 1570713416);
}
$identifier = $subject->getElementId();
if (isset($this->useCollection[$identifier])) {
$this->useCollection[$identifier]->increment();
return;
}
$this->useCollection[$identifier] = new Usage($subject);
}
/**
* @param Subject $subject
*/
public function addUsedIn(Subject $subject)
{
if ($subject === $this) {
throw new \LogicException('Cannot add self as usage', 1570713417);
}
$identifier = $subject->getElementId();
if (isset($this->usedInCollection[$identifier])) {
$this->usedInCollection[$identifier]->increment();
return;
}
$this->usedInCollection[$identifier] = new Usage($subject);
}
/**
* @param bool $accumulated
* @return int
*/
public function countUse($accumulated = false)
{
$count = 0;
foreach ($this->useCollection as $use) {
$useCount = $use->getSubject()->countUse();
$count += $use->getCount() * ($accumulated ? 1 + $useCount : max(1, $useCount));
}
return $count;
}
/**
* @return int
*/
public function countUsedIn()
{
$count = 0;
foreach ($this->usedInCollection as $usedIn) {
$count += $usedIn->getCount() * max(1, $usedIn->getSubject()->countUsedIn());
}
return $count;
}
/**
* Clear the internal arrays (to free up memory as they can get big)
* and return all the child usages DOMElement's
*
* @return array
*/
public function clearInternalAndGetAffectedElements()
{
$elements = array_map(function(Usage $usage) {
return $usage->getSubject()->getElement();
}, $this->useCollection);
$this->usedInCollection = [];
$this->useCollection = [];
return $elements;
}
}

49
lib/svg-sanitizer/src/ElementReference/Usage.php

@ -0,0 +1,49 @@
<?php
namespace enshrined\svgSanitize\ElementReference;
class Usage
{
/**
* @var Subject
*/
protected $subject;
/**
* @var int
*/
protected $count;
/**
* @param Subject $subject
* @param int $count
*/
public function __construct(Subject $subject, $count = 1)
{
$this->subject = $subject;
$this->count = (int)$count;
}
/**
* @param int $by
*/
public function increment($by = 1)
{
$this->count += (int)$by;
}
/**
* @return Subject
*/
public function getSubject()
{
return $this->subject;
}
/**
* @return int
*/
public function getCount()
{
return $this->count;
}
}

39
lib/svg-sanitizer/src/Exceptions/NestingException.php

@ -0,0 +1,39 @@
<?php
namespace enshrined\svgSanitize\Exceptions;
use Exception;
class NestingException extends \Exception
{
/**
* @var \DOMElement
*/
protected $element;
/**
* NestingException constructor.
*
* @param string $message
* @param int $code
* @param Exception|null $previous
* @param \DOMElement|null $element
*/
public function __construct($message = "", $code = 0, Exception $previous = null, \DOMElement $element = null)
{
$this->element = $element;
parent::__construct($message, $code, $previous);
}
/**
* Get the element that caused the exception.
*
* @return \DOMElement
*/
public function getElement()
{
return $this->element;
}
}

53
lib/svg-sanitizer/src/Helper.php

@ -0,0 +1,53 @@
<?php
namespace enshrined\svgSanitize;
class Helper
{
/**
* @param \DOMElement $element
* @return string|null
*/
public static function getElementHref(\DOMElement $element)
{
if ($element->hasAttribute('href')) {
return $element->getAttribute('href');
}
if ($element->hasAttributeNS('http://www.w3.org/1999/xlink', 'href')) {
return $element->getAttributeNS('http://www.w3.org/1999/xlink', 'href');
}
return null;
}
/**
* @param string $href
* @return string|null
*/
public static function extractIdReferenceFromHref($href)
{
if (!is_string($href) || strpos($href, '#') !== 0) {
return null;
}
return substr($href, 1);
}
/**
* @param \DOMElement $needle
* @param \DOMElement $haystack
* @return bool
*/
public static function isElementContainedIn(\DOMElement $needle, \DOMElement $haystack)
{
if ($needle === $haystack) {
return true;
}
foreach ($haystack->childNodes as $childNode) {
if (!$childNode instanceof \DOMElement) {
continue;
}
if (self::isElementContainedIn($needle, $childNode)) {
return true;
}
}
return false;
}
}

630
lib/svg-sanitizer/src/Sanitizer.php

@ -0,0 +1,630 @@
<?php
namespace enshrined\svgSanitize;
use enshrined\svgSanitize\data\AllowedAttributes;
use enshrined\svgSanitize\data\AllowedTags;
use enshrined\svgSanitize\data\AttributeInterface;
use enshrined\svgSanitize\data\TagInterface;
use enshrined\svgSanitize\data\XPath;
use enshrined\svgSanitize\ElementReference\Resolver;
use enshrined\svgSanitize\ElementReference\Subject;
/**
* Class Sanitizer
*
* @package enshrined\svgSanitize
*/
class Sanitizer
{
/**
* @var \DOMDocument
*/
protected $xmlDocument;
/**
* @var array
*/
protected $allowedTags;
/**
* @var array
*/
protected $allowedAttrs;
/**
* @var
*/
protected $xmlLoaderValue;
/**
* @var bool
*/
protected $minifyXML = false;
/**
* @var bool
*/
protected $removeRemoteReferences = false;
/**
* @var int
*/
protected $useThreshold = 1000;
/**
* @var bool
*/
protected $removeXMLTag = false;
/**
* @var int
*/
protected $xmlOptions = LIBXML_NOEMPTYTAG;
/**
* @var array
*/
protected $xmlIssues = array();
/**
* @var Resolver
*/
protected $elementReferenceResolver;
/**
* @var int
*/
protected $useNestingLimit = 15;
/**
*
*/
function __construct()
{
// Load default tags/attributes
$this->allowedAttrs = array_map('strtolower', AllowedAttributes::getAttributes());
$this->allowedTags = array_map('strtolower', AllowedTags::getTags());
}
/**
* Set up the DOMDocument
*/
protected function resetInternal()
{
$this->xmlDocument = new \DOMDocument();
$this->xmlDocument->preserveWhiteSpace = false;
$this->xmlDocument->strictErrorChecking = false;
$this->xmlDocument->formatOutput = !$this->minifyXML;
}
/**
* Set XML options to use when saving XML
* See: DOMDocument::saveXML
*
* @param int $xmlOptions
*/
public function setXMLOptions($xmlOptions)
{
$this->xmlOptions = $xmlOptions;
}
/**
* Get XML options to use when saving XML
* See: DOMDocument::saveXML
*
* @return int
*/
public function getXMLOptions()
{
return $this->xmlOptions;
}
/**
* Get the array of allowed tags
*
* @return array
*/
public function getAllowedTags()
{
return $this->allowedTags;
}
/**
* Set custom allowed tags
*
* @param TagInterface $allowedTags
*/
public function setAllowedTags(TagInterface $allowedTags)
{
$this->allowedTags = array_map('strtolower', $allowedTags::getTags());
}
/**
* Get the array of allowed attributes
*
* @return array
*/
public function getAllowedAttrs()
{
return $this->allowedAttrs;
}
/**
* Set custom allowed attributes
*
* @param AttributeInterface $allowedAttrs
*/
public function setAllowedAttrs(AttributeInterface $allowedAttrs)
{
$this->allowedAttrs = array_map('strtolower', $allowedAttrs::getAttributes());
}
/**
* Should we remove references to remote files?
*
* @param bool $removeRemoteRefs
*/
public function removeRemoteReferences($removeRemoteRefs = false)
{
$this->removeRemoteReferences = $removeRemoteRefs;
}
/**
* Get XML issues.
*
* @return array
*/
public function getXmlIssues() {
return $this->xmlIssues;
}
/**
* Sanitize the passed string
*
* @param string $dirty
* @return string
*/
public function sanitize($dirty)
{
// Don't run on an empty string
if (empty($dirty)) {
return '';
}
// Strip php tags
$dirty = preg_replace('/<\?(=|php)(.+?)\?>/i', '', $dirty);
$this->resetInternal();
$this->setUpBefore();
$loaded = $this->xmlDocument->loadXML($dirty);
// If we couldn't parse the XML then we go no further. Reset and return false
if (!$loaded) {
$this->resetAfter();
return false;
}
// Pre-process all identified elements
$xPath = new XPath($this->xmlDocument);
$this->elementReferenceResolver = new Resolver($xPath, $this->useNestingLimit);
$this->elementReferenceResolver->collect();
$elementsToRemove = $this->elementReferenceResolver->getElementsToRemove();
// Grab all the elements
$allElements = $this->xmlDocument->getElementsByTagName("*");
// remove doctype after node elements have been analyzed
$this->removeDoctype();
// Start the cleaning proccess
$this->startClean($allElements, $elementsToRemove);
// Save cleaned XML to a variable
if ($this->removeXMLTag) {
$clean = $this->xmlDocument->saveXML($this->xmlDocument->documentElement, $this->xmlOptions);
} else {
$clean = $this->xmlDocument->saveXML($this->xmlDocument, $this->xmlOptions);
}
$this->resetAfter();
// Remove any extra whitespaces when minifying
if ($this->minifyXML) {
$clean = preg_replace('/\s+/', ' ', $clean);
}
// Return result
return $clean;
}
/**
* Set up libXML before we start
*/
protected function setUpBefore()
{
// This function has been deprecated in PHP 8.0 because in libxml 2.9.0, external entity loading is
// disabled by default, so this function is no longer needed to protect against XXE attacks.
if (\LIBXML_VERSION < 20900) {
// Turn off the entity loader
$this->xmlLoaderValue = libxml_disable_entity_loader(true);
}
// Suppress the errors because we don't really have to worry about formation before cleansing
libxml_use_internal_errors(true);
// Reset array of altered XML
$this->xmlIssues = array();
}
/**
* Reset the class after use
*/
protected function resetAfter()
{
// This function has been deprecated in PHP 8.0 because in libxml 2.9.0, external entity loading is
// disabled by default, so this function is no longer needed to protect against XXE attacks.
if (\LIBXML_VERSION < 20900) {
// Reset the entity loader
libxml_disable_entity_loader($this->xmlLoaderValue);
}
}
/**
* Remove the XML Doctype
* It may be caught later on output but that seems to be buggy, so we need to make sure it's gone
*/
protected function removeDoctype()
{
foreach ($this->xmlDocument->childNodes as $child) {
if ($child->nodeType === XML_DOCUMENT_TYPE_NODE) {
$child->parentNode->removeChild($child);
}
}
}
/**
* Start the cleaning with tags, then we move onto attributes and hrefs later
*
* @param \DOMNodeList $elements
* @param array $elementsToRemove
*/
protected function startClean(\DOMNodeList $elements, array $elementsToRemove)
{
// loop through all elements
// we do this backwards so we don't skip anything if we delete a node
// see comments at: http://php.net/manual/en/class.domnamednodemap.php
for ($i = $elements->length - 1; $i >= 0; $i--) {
/** @var \DOMElement $currentElement */
$currentElement = $elements->item($i);
/**
* If the element has exceeded the nesting limit, we should remove it.
*
* As it's only <use> elements that cause us issues with nesting DOS attacks
* we should check what the element is before removing it. For now we'll only
* remove <use> elements.
*/
if (in_array($currentElement, $elementsToRemove) && 'use' === $currentElement->nodeName) {
$currentElement->parentNode->removeChild($currentElement);
$this->xmlIssues[] = array(
'message' => 'Invalid \'' . $currentElement->tagName . '\'',
'line' => $currentElement->getLineNo(),
);
continue;
}
// If the tag isn't in the whitelist, remove it and continue with next iteration
if (!in_array(strtolower($currentElement->tagName), $this->allowedTags)) {
$currentElement->parentNode->removeChild($currentElement);
$this->xmlIssues[] = array(
'message' => 'Suspicious tag \'' . $currentElement->tagName . '\'',
'line' => $currentElement->getLineNo(),
);
continue;
}
$this->cleanHrefs($currentElement);
$this->cleanXlinkHrefs($currentElement);
$this->cleanAttributesOnWhitelist($currentElement);
if (strtolower($currentElement->tagName) === 'use') {
if ($this->isUseTagDirty($currentElement)
|| $this->isUseTagExceedingThreshold($currentElement)
) {
$currentElement->parentNode->removeChild($currentElement);
$this->xmlIssues[] = array(
'message' => 'Suspicious \'' . $currentElement->tagName . '\'',
'line' => $currentElement->getLineNo(),
);
continue;
}
}
}
}
/**
* Only allow attributes that are on the whitelist
*
* @param \DOMElement $element
*/
protected function cleanAttributesOnWhitelist(\DOMElement $element)
{
for ($x = $element->attributes->length - 1; $x >= 0; $x--) {
// get attribute name
$attrName = $element->attributes->item($x)->name;
// Remove attribute if not in whitelist
if (!in_array(strtolower($attrName), $this->allowedAttrs) && !$this->isAriaAttribute(strtolower($attrName)) && !$this->isDataAttribute(strtolower($attrName))) {
$element->removeAttribute($attrName);
$this->xmlIssues[] = array(
'message' => 'Suspicious attribute \'' . $attrName . '\'',
'line' => $element->getLineNo(),
);
}
/**
* This is used for when a namespace isn't imported properly.
* Such as xlink:href when the xlink namespace isn't imported.
* We have to do this as the link is still ran in this case.
*/
if (false !== strpos($attrName, 'href')) {
$href = $element->getAttribute($attrName);
if (false === $this->isHrefSafeValue($href)) {
$element->removeAttribute($attrName);
$this->xmlIssues[] = array(
'message' => 'Suspicious attribute \'href\'',
'line' => $element->getLineNo(),
);
}
}
// Do we want to strip remote references?
if($this->removeRemoteReferences) {
// Remove attribute if it has a remote reference
if (isset($element->attributes->item($x)->value) && $this->hasRemoteReference($element->attributes->item($x)->value)) {
$element->removeAttribute($attrName);
$this->xmlIssues[] = array(
'message' => 'Suspicious attribute \'' . $attrName . '\'',
'line' => $element->getLineNo(),
);
}
}
}
}
/**
* Clean the xlink:hrefs of script and data embeds
*
* @param \DOMElement $element
*/
protected function cleanXlinkHrefs(\DOMElement $element)
{
$xlinks = $element->getAttributeNS('http://www.w3.org/1999/xlink', 'href');
if (false === $this->isHrefSafeValue($xlinks)) {
$element->removeAttributeNS( 'http://www.w3.org/1999/xlink', 'href' );
$this->xmlIssues[] = array(
'message' => 'Suspicious attribute \'href\'',
'line' => $element->getLineNo(),
);
}
}
/**
* Clean the hrefs of script and data embeds
*
* @param \DOMElement $element
*/
protected function cleanHrefs(\DOMElement $element)
{
$href = $element->getAttribute('href');
if (false === $this->isHrefSafeValue($href)) {
$element->removeAttribute('href');
$this->xmlIssues[] = array(
'message' => 'Suspicious attribute \'href\'',
'line' => $element->getLineNo(),
);
}
}
/**
* Only allow whitelisted starts to be within the href.
*
* This will stop scripts etc from being passed through, with or without attempting to hide bypasses.
* This stops the need for us to use a complicated script regex.
*
* @param $value
* @return bool
*/
protected function isHrefSafeValue($value) {
// Allow empty values
if (empty($value)) {
return true;
}
// Allow fragment identifiers.
if ('#' === substr($value, 0, 1)) {
return true;
}
// Allow relative URIs.
if ('/' === substr($value, 0, 1)) {
return true;
}
// Allow HTTPS domains.
if ('https://' === substr($value, 0, 8)) {
return true;
}
// Allow HTTP domains.
if ('http://' === substr($value, 0, 7)) {
return true;
}
// Allow known data URIs.
if (in_array(substr($value, 0, 14), array(
'data:image/png', // PNG
'data:image/gif', // GIF
'data:image/jpg', // JPG
'data:image/jpe', // JPEG
'data:image/pjp', // PJPEG
))) {
return true;
}
// Allow known short data URIs.
if (in_array(substr($value, 0, 12), array(
'data:img/png', // PNG
'data:img/gif', // GIF
'data:img/jpg', // JPG
'data:img/jpe', // JPEG
'data:img/pjp', // PJPEG
))) {
return true;
}
return false;
}
/**
* Removes non-printable ASCII characters from string & trims it
*
* @param string $value
* @return bool
*/
protected function removeNonPrintableCharacters($value)
{
return trim(preg_replace('/[^ -~]/xu','',$value));
}
/**
* Does this attribute value have a remote reference?
*
* @param $value
* @return bool
*/
protected function hasRemoteReference($value)
{
$value = $this->removeNonPrintableCharacters($value);
$wrapped_in_url = preg_match('~^url\(\s*[\'"]\s*(.*)\s*[\'"]\s*\)$~xi', $value, $match);
if (!$wrapped_in_url){
return false;
}
$value = trim($match[1], '\'"');
return preg_match('~^((https?|ftp|file):)?//~xi', $value);
}
/**
* Should we minify the output?
*
* @param bool $shouldMinify
*/
public function minify($shouldMinify = false)
{
$this->minifyXML = (bool) $shouldMinify;
}
/**
* Should we remove the XML tag in the header?
*
* @param bool $removeXMLTag
*/
public function removeXMLTag($removeXMLTag = false)
{
$this->removeXMLTag = (bool) $removeXMLTag;
}
/**
* Whether `<use ... xlink:href="#identifier">` elements shall be
* removed in case expansion would exceed this threshold.
*
* @param int $useThreshold
*/
public function useThreshold($useThreshold = 1000)
{
$this->useThreshold = (int)$useThreshold;
}
/**
* Check to see if an attribute is an aria attribute or not
*
* @param $attributeName
*
* @return bool
*/
protected function isAriaAttribute($attributeName)
{
return strpos($attributeName, 'aria-') === 0;
}
/**
* Check to see if an attribute is an data attribute or not
*
* @param $attributeName
*
* @return bool
*/
protected function isDataAttribute($attributeName)
{
return strpos($attributeName, 'data-') === 0;
}
/**
* Make sure our use tag is only referencing internal resources
*
* @param \DOMElement $element
* @return bool
*/
protected function isUseTagDirty(\DOMElement $element)
{
$href = Helper::getElementHref($element);
return $href && strpos($href, '#') !== 0;
}
/**
* Determines whether `<use ... xlink:href="#identifier">` is expanded
* recursively in order to create DoS scenarios. The amount of a actually
* used element needs to be below `$this->useThreshold`.
*
* @param \DOMElement $element
* @return bool
*/
protected function isUseTagExceedingThreshold(\DOMElement $element)
{
if ($this->useThreshold <= 0) {
return false;
}
$useId = Helper::extractIdReferenceFromHref(
Helper::getElementHref($element)
);
if ($useId === null) {
return false;
}
foreach ($this->elementReferenceResolver->findByElementId($useId) as $subject) {
if ($subject->countUse() >= $this->useThreshold) {
return true;
}
}
return false;
}
/**
* Set the nesting limit for <use> tags.
*
* @param $limit
*/
public function setUseNestingLimit($limit)
{
$this->useNestingLimit = (int) $limit;
}
}

357
lib/svg-sanitizer/src/data/AllowedAttributes.php

@ -0,0 +1,357 @@
<?php
namespace enshrined\svgSanitize\data;
/**
* Class AllowedAttributes
*
* @package enshrined\svgSanitize\data
*/
class AllowedAttributes implements AttributeInterface
{
/**
* Returns an array of attributes
*
* @return array
*/
public static function getAttributes()
{
return array(
// HTML
'about',
'accept',
'action',
'align',
'alt',
'autocomplete',
'background',
'bgcolor',
'border',
'cellpadding',
'cellspacing',
'checked',
'cite',
'class',
'clear',
'color',
'cols',
'colspan',
'coords',
'crossorigin',
'datetime',
'default',
'dir',
'disabled',
'download',
'enctype',
'encoding',
'face',
'for',
'headers',
'height',
'hidden',
'high',
'href',
'hreflang',
'id',
'integrity',
'ismap',
'label',
'lang',
'list',
'loop',
'low',
'max',
'maxlength',
'media',
'method',
'min',
'multiple',
'name',
'noshade',
'novalidate',
'nowrap',
'open',
'optimum',
'pattern',
'placeholder',
'poster',
'preload',
'pubdate',
'radiogroup',
'readonly',
'rel',
'required',
'rev',
'reversed',
'role',
'rows',
'rowspan',
'spellcheck',
'scope',
'selected',
'shape',
'size',
'sizes',
'span',
'srclang',
'start',
'src',
'srcset',
'step',
'style',
'summary',
'tabindex',
'title',
'type',
'usemap',
'valign',
'value',
'version',
'width',
'xmlns',