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Added untrusted server fetching control 

WKHTMLtoPDF provides limited control for external fetching
so that will now be disabled by default unless
ALLOW_UNTRUSTED_SERVER_FETCHING=true is specifically set.
This new option will also control DOMPDF fetching.
This commit is contained in:
Dan Brown 2021-08-31 20:22:42 +01:00
parent 8f12c8bc99
commit bee5e2c7ca
No known key found for this signature in database
GPG Key ID: 46D9F943C24A2EF9
7 changed files with 52 additions and 18 deletions
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6
.env.example.complete
View File

@ -281,6 +281,12 @@ ALLOW_CONTENT_SCRIPTS=false
# Contents of the robots.txt file can be overridden, making this option obsolete.
ALLOW_ROBOTS=null
# Allow server-side fetches to be performed to potentially unknown
# and user-provided locations. Primarily used in exports when loading
# in externally referenced assets.
# Can be 'true' or 'false'.
ALLOW_UNTRUSTED_SERVER_FETCHING=false
# A list of hosts that BookStack can be iframed within.
# Space separated if multiple. BookStack host domain is auto-inferred.
# For Example: ALLOWED_IFRAME_HOSTS="https://example.com https://a.example.com"

5
app/Config/app.php
View File

@ -36,6 +36,11 @@ return [
// Even when overridden the WYSIWYG editor may still escape script content.
'allow_content_scripts' => env('ALLOW_CONTENT_SCRIPTS', false),
# Allow server-side fetches to be performed to potentially unknown
# and user-provided locations. Primarily used in exports when loading
# in externally referenced assets.
'allow_untrusted_server_fetching' => env('ALLOW_UNTRUSTED_SERVER_FETCHING', false),
// Override the default behaviour for allowing crawlers to crawl the instance.
// May be ignored if view has be overridden or modified.
// Defaults to null since, if not set, 'app-public' status used instead.

34
app/Config/dompdf.php
View File

@ -37,7 +37,7 @@ return [
* Times-Roman, Times-Bold, Times-BoldItalic, Times-Italic,
* Symbol, ZapfDingbats.
*/
'DOMPDF_FONT_DIR' => storage_path('fonts/'), // advised by dompdf (https://github.com/dompdf/dompdf/pull/782)
'font_dir' => storage_path('fonts/'), // advised by dompdf (https://github.com/dompdf/dompdf/pull/782)
/**
* The location of the DOMPDF font cache directory.
@ -47,7 +47,7 @@ return [
*
* Note: This directory must exist and be writable by the webserver process.
*/
'DOMPDF_FONT_CACHE' => storage_path('fonts/'),
'font_cache' => storage_path('fonts/'),
/**
* The location of a temporary directory.
@ -56,7 +56,7 @@ return [
* The temporary directory is required to download remote images and when
* using the PFDLib back end.
*/
'DOMPDF_TEMP_DIR' => sys_get_temp_dir(),
'temp_dir' => sys_get_temp_dir(),
/**
* ==== IMPORTANT ====.
@ -70,7 +70,7 @@ return [
* direct class use like:
* $dompdf = new DOMPDF(); $dompdf->load_html($htmldata); $dompdf->render(); $pdfdata = $dompdf->output();
*/
'DOMPDF_CHROOT' => realpath(base_path()),
'chroot' => realpath(base_path()),
/**
* Whether to use Unicode fonts or not.
@ -81,12 +81,12 @@ return [
* When enabled, dompdf can support all Unicode glyphs. Any glyphs used in a
* document must be present in your fonts, however.
*/
'DOMPDF_UNICODE_ENABLED' => true,
'unicode_enabled' => true,
/**
* Whether to enable font subsetting or not.
*/
'DOMPDF_ENABLE_FONTSUBSETTING' => false,
'enable_fontsubsetting' => false,
/**
* The PDF rendering backend to use.
@ -115,7 +115,7 @@ return [
* @link http://www.ros.co.nz/pdf
* @link http://www.php.net/image
*/
'DOMPDF_PDF_BACKEND' => 'CPDF',
'pdf_backend' => 'CPDF',
/**
* PDFlib license key.
@ -141,7 +141,7 @@ return [
* the desired content might be different (e.g. screen or projection view of html file).
* Therefore allow specification of content here.
*/
'DOMPDF_DEFAULT_MEDIA_TYPE' => 'print',
'default_media_type' => 'print',
/**
* The default paper size.
@ -150,7 +150,7 @@ return [
*
* @see CPDF_Adapter::PAPER_SIZES for valid sizes ('letter', 'legal', 'A4', etc.)
*/
'DOMPDF_DEFAULT_PAPER_SIZE' => 'a4',
'default_paper_size' => 'a4',
/**
* The default font family.
@ -159,7 +159,7 @@ return [
*
* @var string
*/
'DOMPDF_DEFAULT_FONT' => 'dejavu sans',
'default_font' => 'dejavu sans',
/**
* Image DPI setting.
@ -194,7 +194,7 @@ return [
*
* @var int
*/
'DOMPDF_DPI' => 96,
'dpi' => 96,
/**
* Enable inline PHP.
@ -208,7 +208,7 @@ return [
*
* @var bool
*/
'DOMPDF_ENABLE_PHP' => false,
'enable_php' => false,
/**
* Enable inline Javascript.
@ -218,7 +218,7 @@ return [
*
* @var bool
*/
'DOMPDF_ENABLE_JAVASCRIPT' => false,
'enable_javascript' => false,
/**
* Enable remote file access.
@ -237,12 +237,12 @@ return [
*
* @var bool
*/
'DOMPDF_ENABLE_REMOTE' => true,
'enable_remote' => env('ALLOW_UNTRUSTED_SERVER_FETCHING', false),
/**
* A ratio applied to the fonts height to be more like browsers' line height.
*/
'DOMPDF_FONT_HEIGHT_RATIO' => 1.1,
'font_height_ratio' => 1.1,
/**
* Enable CSS float.
@ -251,12 +251,12 @@ return [
*
* @var bool
*/
'DOMPDF_ENABLE_CSS_FLOAT' => true,
'enable_css_float' => true,
/**
* Use the more-than-experimental HTML5 Lib parser.
*/
'DOMPDF_ENABLE_HTML5PARSER' => true,
'enable_html5parser' => true,
],

2
app/Entities/Tools/ExportFormatter.php
View File

@ -140,7 +140,7 @@ class ExportFormatter
protected function htmlToPdf(string $html): string
{
$containedHtml = $this->containHtml($html);
$useWKHTML = config('snappy.pdf.binary') !== false;
$useWKHTML = config('snappy.pdf.binary') !== false && config('app.allow_untrusted_server_fetching') === true;
if ($useWKHTML) {
$pdf = SnappyPDF::loadHTML($containedHtml);
$pdf->setOption('print-media-type', true);

1
phpunit.xml
View File

@ -37,6 +37,7 @@
<server name="LOG_CHANNEL" value="single"/>
<server name="AUTH_METHOD" value="standard"/>
<server name="DISABLE_EXTERNAL_SERVICES" value="true"/>
<server name="ALLOW_UNTRUSTED_SERVER_FETCHING" value="false"/>
<server name="AVATAR_URL" value=""/>
<server name="LDAP_START_TLS" value="false"/>
<server name="LDAP_VERSION" value="3"/>

16
tests/Entity/ExportTest.php
View File

@ -366,4 +366,20 @@ class ExportTest extends TestCase
$this->assertPermissionError($resp);
}
}
public function test_wkhtmltopdf_only_used_when_allow_untrusted_is_true()
{
/** @var Page $page */
$page = Page::query()->first();
config()->set('snappy.pdf.binary', '/abc123');
config()->set('app.allow_untrusted_server_fetching', false);
$resp = $this->asEditor()->get($page->getUrl('/export/pdf'));
$resp->assertStatus(200); // Sucessful response with invalid snappy binary indicates dompdf usage.
config()->set('app.allow_untrusted_server_fetching', true);
$resp = $this->get($page->getUrl('/export/pdf'));
$resp->assertStatus(500); // Bad response indicates wkhtml usage
}
}

6
tests/Unit/ConfigTest.php
View File

@ -76,6 +76,12 @@ class ConfigTest extends TestCase
);
}
public function test_dompdf_remote_fetching_controlled_by_allow_untrusted_server_fetching_false()
{
$this->checkEnvConfigResult('ALLOW_UNTRUSTED_SERVER_FETCHING', 'false', 'dompdf.defines.enable_remote', false);
$this->checkEnvConfigResult('ALLOW_UNTRUSTED_SERVER_FETCHING', 'true', 'dompdf.defines.enable_remote', true);
}
/**
* Set an environment variable of the given name and value
* then check the given config key to see if it matches the given result.