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Added safe mime sniffing to prevent serving HTML

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(Amoung other content types)
For #3027
This commit is contained in:
Dan Brown 2021-10-31 17:58:56 +00:00
parent 5c834f24a6
commit ae155d6745
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GPG key ID: 46D9F943C24A2EF9
3 changed files with 106 additions and 6 deletions
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15
app/Http/Controllers/Controller.php
View file

@ -5,6 +5,7 @@ namespace BookStack\Http\Controllers;
use BookStack\Facades\Activity;
use BookStack\Interfaces\Loggable;
use BookStack\Model;
use BookStack\Util\WebSafeMimeSniffer;
use finfo;
use Illuminate\Foundation\Bus\DispatchesJobs;
use Illuminate\Foundation\Validation\ValidatesRequests;
@ -117,8 +118,9 @@ abstract class Controller extends BaseController
protected function downloadResponse(string $content, string $fileName): Response
{
return response()->make($content, 200, [
'Content-Type' => 'application/octet-stream',
'Content-Disposition' => 'attachment; filename="' . $fileName . '"',
'Content-Type' => 'application/octet-stream',
'Content-Disposition' => 'attachment; filename="' . $fileName . '"',
'X-Content-Type-Options' => 'nosniff',
]);
}
@ -128,12 +130,13 @@ abstract class Controller extends BaseController
*/
protected function inlineDownloadResponse(string $content, string $fileName): Response
{
$finfo = new finfo(FILEINFO_MIME_TYPE);
$mime = $finfo->buffer($content) ?: 'application/octet-stream';
$mime = (new WebSafeMimeSniffer)->sniff($content);
return response()->make($content, 200, [
'Content-Type' => $mime,
'Content-Disposition' => 'inline; filename="' . $fileName . '"',
'Content-Type' => $mime,
'Content-Disposition' => 'inline; filename="' . $fileName . '"',
'X-Content-Type-Options' => 'nosniff',
]);
}

65
app/Util/WebSafeMimeSniffer.php Normal file
View file

@ -0,0 +1,65 @@
<?php
namespace BookStack\Util;
use finfo;
/**
* Helper class to sniff out the mime-type of content resulting in
* a mime-type that's relatively safe to serve to a browser.
*/
class WebSafeMimeSniffer
{
/**
* @var string[]
*/
protected $safeMimes = [
'application/json',
'application/octet-stream',
'application/pdf',
'image/bmp',
'image/jpeg',
'image/png',
'image/gif',
'image/webp',
'image/avif',
'image/heic',
'text/css',
'text/csv',
'text/javascript',
'text/json',
'text/plain',
'video/x-msvideo',
'video/mp4',
'video/mpeg',
'video/ogg',
'video/webm',
'video/vp9',
'video/h264',
'video/av1',
];
/**
* Sniff the mime-type from the given file content while running the result
* through an allow-list to ensure a web-safe result.
* Takes the content as a reference since the value may be quite large.
*/
public function sniff(string &$content): string
{
$fInfo = new finfo(FILEINFO_MIME_TYPE);
$mime = $fInfo->buffer($content) ?: 'application/octet-stream';
if (in_array($mime, $this->safeMimes)) {
return $mime;
}
[$category] = explode('/', $mime, 2);
if ($category === 'text') {
return 'text/plain';
}
return 'application/octet-stream';
}
}

32
tests/Uploads/AttachmentTest.php
View file

@ -9,6 +9,7 @@ use BookStack\Uploads\Attachment;
use BookStack\Uploads\AttachmentService;
use Illuminate\Http\UploadedFile;
use Tests\TestCase;
use Tests\TestResponse;
class AttachmentTest extends TestCase
{
@ -44,6 +45,20 @@ class AttachmentTest extends TestCase
return Attachment::query()->latest()->first();
}
/**
* Create a new upload attachment from the given data.
*/
protected function createUploadAttachment(Page $page, string $filename, string $content, string $mimeType): Attachment
{
$file = tmpfile();
$filePath = stream_get_meta_data($file)['uri'];
file_put_contents($filePath, $content);
$upload = new UploadedFile($filePath, $filename, $mimeType, null, true);
$this->call('POST', '/attachments/upload', ['uploaded_to' => $page->id], [], ['file' => $upload], []);
return $page->attachments()->latest()->firstOrFail();
}
/**
* Delete all uploaded files.
* To assist with cleanup.
@ -305,7 +320,24 @@ class AttachmentTest extends TestCase
// http-foundation/Response does some 'fixing' of responses to add charsets to text responses.
$attachmentGet->assertHeader('Content-Type', 'text/plain; charset=UTF-8');
$attachmentGet->assertHeader('Content-Disposition', 'inline; filename="upload_test_file.txt"');
$attachmentGet->assertHeader('X-Content-Type-Options', 'nosniff');
$this->deleteUploads();
}
public function test_html_file_access_with_open_forces_plain_content_type()
{
$page = Page::query()->first();
$this->asAdmin();
$attachment = $this->createUploadAttachment($page, 'test_file.html', '<html></html><p>testing</p>', 'text/html');
$attachmentGet = $this->get($attachment->getUrl(true));
// http-foundation/Response does some 'fixing' of responses to add charsets to text responses.
$attachmentGet->assertHeader('Content-Type', 'text/plain; charset=UTF-8');
$attachmentGet->assertHeader('Content-Disposition', 'inline; filename="test_file.html"');
$this->deleteUploads();
}
}