Security: Added new SSR allow list and validator

Included unit tests to cover validator functionality.
Added to webhooks.
Still need to do testing specifically for webhooks.
This commit is contained in:
Dan Brown 2023-08-26 15:28:29 +01:00
parent 9100a82b47
commit c324ad928d
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5 changed files with 137 additions and 0 deletions

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@ -8,6 +8,7 @@ use BookStack\Activity\Tools\WebhookFormatter;
use BookStack\Facades\Theme;
use BookStack\Theming\ThemeEvents;
use BookStack\Users\Models\User;
use BookStack\Util\SsrUrlValidator;
use Illuminate\Bus\Queueable;
use Illuminate\Contracts\Queue\ShouldQueue;
use Illuminate\Foundation\Bus\Dispatchable;
@ -53,6 +54,8 @@ class DispatchWebhookJob implements ShouldQueue
$lastError = null;
try {
(new SsrUrlValidator())->ensureAllowed($this->webhook->endpoint);
$response = Http::asJson()
->withOptions(['allow_redirects' => ['strict' => true]])
->timeout($this->webhook->timeout)

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@ -66,6 +66,15 @@ return [
// Current host and source for the "DRAWIO" setting will be auto-appended to the sources configured.
'iframe_sources' => env('ALLOWED_IFRAME_SOURCES', 'https://*.draw.io https://*.youtube.com https://*.youtube-nocookie.com https://*.vimeo.com'),
// A list of the sources/hostnames that can be reached by application SSR calls.
// This is used wherever users can provide URLs/hosts in-platform, like for webhooks.
// Host-specific functionality (usually controlled via other options) like auth
// or user avatars for example, won't use this list.
// Space seperated if multiple. Can use '*' as a wildcard.
// Values will be compared prefix-matched, case-insensitive, against called SSR urls.
// Defaults to allow all hosts.
'ssr_hosts' => env('ALLOWED_SSR_HOSTS', '*'),
// Alter the precision of IP addresses stored by BookStack.
// Integer value between 0 (IP hidden) to 4 (Full IP usage)
'ip_address_precision' => env('IP_ADDRESS_PRECISION', 4),

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@ -0,0 +1,64 @@
<?php
namespace BookStack\Util;
use BookStack\Exceptions\HttpFetchException;
class SsrUrlValidator
{
protected string $config;
public function __construct(string $config = null)
{
$this->config = $config ?? config('app.ssr_hosts') ?? '';
}
/**
* @throws HttpFetchException
*/
public function ensureAllowed(string $url): void
{
if (!$this->allowed($url)) {
throw new HttpFetchException(trans('errors.http_ssr_url_no_match'));
}
}
/**
* Check if the given URL is allowed by the configured SSR host values.
*/
public function allowed(string $url): bool
{
$allowed = $this->getHostPatterns();
foreach ($allowed as $pattern) {
if ($this->urlMatchesPattern($url, $pattern)) {
return true;
}
}
return false;
}
protected function urlMatchesPattern($url, $pattern): bool
{
$pattern = trim($pattern);
$url = trim($url);
if (empty($pattern) || empty($url)) {
return false;
}
$quoted = preg_quote($pattern, '/');
$regexPattern = str_replace('\*', '.*', $quoted);
return preg_match('/^' . $regexPattern . '.*$/i', $url);
}
/**
* @return string[]
*/
protected function getHostPatterns(): array
{
return explode(' ', strtolower($this->config));
}
}

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@ -111,4 +111,6 @@ return [
// Settings & Maintenance
'maintenance_test_email_failure' => 'Error thrown when sending a test email:',
// HTTP errors
'http_ssr_url_no_match' => 'The URL does not match the configured allowed SSR hosts',
];

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@ -0,0 +1,59 @@
<?php
namespace Tests\Unit;
use BookStack\Exceptions\HttpFetchException;
use BookStack\Util\SsrUrlValidator;
use Tests\TestCase;
class SsrUrlValidatorTest extends TestCase
{
public function test_allowed()
{
$testMap = [
// Single values
['config' => '', 'url' => '', 'result' => false],
['config' => '', 'url' => 'https://example.com', 'result' => false],
['config' => ' ', 'url' => 'https://example.com', 'result' => false],
['config' => '*', 'url' => '', 'result' => false],
['config' => '*', 'url' => 'https://example.com', 'result' => true],
['config' => 'https://*', 'url' => 'https://example.com', 'result' => true],
['config' => 'http://*', 'url' => 'https://example.com', 'result' => false],
['config' => 'https://*example.com', 'url' => 'https://example.com', 'result' => true],
['config' => 'https://*ample.com', 'url' => 'https://example.com', 'result' => true],
['config' => 'https://*.example.com', 'url' => 'https://example.com', 'result' => false],
['config' => 'https://*.example.com', 'url' => 'https://test.example.com', 'result' => true],
['config' => '*//example.com', 'url' => 'https://example.com', 'result' => true],
['config' => '*//example.com', 'url' => 'http://example.com', 'result' => true],
['config' => 'https://example.com', 'url' => 'https://example.com/a/b/c?test=cat', 'result' => true],
['config' => 'https://example.com', 'url' => 'https://example.co.uk', 'result' => false],
// Escapes
['config' => 'https://(.*?).com', 'url' => 'https://example.com', 'result' => false],
['config' => 'https://example.com', 'url' => 'https://example.co.uk#https://example.com', 'result' => false],
// Multi values
['config' => '*//example.org *//example.com', 'url' => 'https://example.com', 'result' => true],
['config' => '*//example.org *//example.com', 'url' => 'https://example.com/a/b/c?test=cat#hello', 'result' => true],
['config' => '*.example.org *.example.com', 'url' => 'https://example.co.uk', 'result' => false],
['config' => ' *.example.org *.example.com ', 'url' => 'https://example.co.uk', 'result' => false],
['config' => '* *.example.com', 'url' => 'https://example.co.uk', 'result' => true],
['config' => '*//example.org *//example.com *//example.co.uk', 'url' => 'https://example.co.uk', 'result' => true],
['config' => '*//example.org *//example.com *//example.co.uk', 'url' => 'https://example.net', 'result' => false],
];
foreach ($testMap as $test) {
$result = (new SsrUrlValidator($test['config']))->allowed($test['url']);
$this->assertEquals($test['result'], $result, "Failed asserting url '{$test['url']}' with config '{$test['config']}' results " . ($test['result'] ? 'true' : 'false'));
}
}
public function test_enssure_allowed()
{
$result = (new SsrUrlValidator('https://example.com'))->ensureAllowed('https://example.com');
$this->assertNull($result);
$this->expectException(HttpFetchException::class);
(new SsrUrlValidator('https://example.com'))->ensureAllowed('https://test.example.com');
}
}