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Provide a setting which forces all file views to be served from an alternate

domain

Summary:
See D758, D759.

  - Provide a strongly recommended setting which permits configuration of an
alternate domain.
  - Lock cookies down better: set them on the exact domain, and use SSL-only if
the configuration is HTTPS.
  - Prevent Phabriator from setting cookies on other domains.

This assumes D759 will land, it is not effective without that change.

Test Plan:
  - Attempted to login from a different domain and was rejected.
  - Logged out, logged back in normally.
  - Put install in setup mode and verified it revealed a warning.
  - Configured an alterate domain.
  - Tried to view an image with an old URI, got a 400.
  - Went to /files/ and verified links rendered to the alternate domain.
  - Viewed an alternate domain file.
  - Tried to view an alternate domain file without the secret key, got a 404.

Reviewers: andrewjcg, erling, aran, tuomaspelkonen, jungejason, codeblock
CC: aran
Differential Revision: 760
This commit is contained in:
epriestley 2011-08-01 22:24:00 -07:00
parent 355b753df7
commit 68c30e1a71
15 changed files with 224 additions and 7 deletions

View file

@ -35,6 +35,35 @@ return array(
// be 50x50px.
'user.default-profile-image-phid' => 'PHID-FILE-4d61229816cfe6f2b2a3',
// -- IMPORTANT! Security! -------------------------------------------------- //
// IMPORTANT: By default, Phabricator serves files from the same domain the
// application lives on. This is convenient but not secure: it creates
// a vulnerability where an external attacker can:
//
// - Convince a privileged user to upload a file which appears to be an
// image or some other inoccuous type of file (the file is actually both
// a JAR and an image); and
// - convince the user to give them the URI for the image; and
// - convince the user to click a link to a site which embeds the "image"
// using an <applet /> tag. This steals the user's credentials.
//
// If the attacker is internal, they can execute the first two steps
// themselves and need only convince another user to click a link in order to
// steal their credentials.
//
// To avoid this, you should configure a second domain in the same way you
// have the primary domain configured (e.g., point it at the same machine and
// set up the same vhost rules) and provide it here. For instance, if your
// primary install is on "http://www.phabricator-example.com/", you could
// configure "http://www.phabricator-files.com/" and specify the entire
// domain (with protocol) here. This will enforce that viewable files are
// served only from the alternate domain. Ideally, you should use a completely
// separate domain name rather than just a different subdomain.
//
// It is STRONGLY RECOMMENDED that you configure this. Phabricator makes this
// attack difficult, but it is viable unless you isolate the file domain.
'security.alternate-file-domain' => null,
// -- DarkConsole ----------------------------------------------------------- //
@ -314,6 +343,12 @@ return array(
// addresses.
'phabricator.mail-key' => '5ce3e7e8787f6e40dfae861da315a5cdf1018f12',
// This is hashed with other inputs to generate file secret keys. Changing
// it will invalidate all file URIs if you have an alternate file domain
// configured (see 'security.alternate-file-domain').
'phabricator.file-key' => 'ade8dadc8b4382067069a4d4798112191af8a190',
// Version string displayed in the footer. You probably should leave this
// alone.
'phabricator.version' => 'UNSTABLE',
@ -338,6 +373,9 @@ return array(
//
// The keys in this array are viewable mime types; the values are the mime
// types they will be delivered as when they are viewed in the browser.
//
// IMPORTANT: Making any file types viewable is a security vulnerability if
// you do not configure 'security.alternate-file-domain' above.
'files.viewable-mime-types' => array(
'image/jpeg' => 'image/jpeg',
'image/jpg' => 'image/jpg',

View file

@ -404,6 +404,7 @@ phutil_register_library_map(array(
'PhabricatorFeedStreamController' => 'applications/feed/controller/stream',
'PhabricatorFeedView' => 'applications/feed/view/base',
'PhabricatorFile' => 'applications/files/storage/file',
'PhabricatorFileAltViewController' => 'applications/files/controller/altview',
'PhabricatorFileController' => 'applications/files/controller/base',
'PhabricatorFileDAO' => 'applications/files/storage/base',
'PhabricatorFileDropUploadController' => 'applications/files/controller/dropupload',
@ -1000,6 +1001,7 @@ phutil_register_library_map(array(
'PhabricatorFeedStreamController' => 'PhabricatorFeedController',
'PhabricatorFeedView' => 'AphrontView',
'PhabricatorFile' => 'PhabricatorFileDAO',
'PhabricatorFileAltViewController' => 'PhabricatorFileController',
'PhabricatorFileController' => 'PhabricatorController',
'PhabricatorFileDAO' => 'PhabricatorLiskDAO',
'PhabricatorFileDropUploadController' => 'PhabricatorFileController',

View file

@ -56,6 +56,7 @@ class AphrontDefaultApplicationConfiguration
'(?P<view>info)/(?P<phid>[^/]+)/' => 'PhabricatorFileViewController',
'(?P<view>view)/(?P<phid>[^/]+)/' => 'PhabricatorFileViewController',
'(?P<view>download)/(?P<phid>[^/]+)/' => 'PhabricatorFileViewController',
'alt/(?<key>[^/]+)/(?<phid>[^/]+)/' => 'PhabricatorFileAltViewController',
'macro/' => array(
'$' => 'PhabricatorFileMacroListController',
'edit/(?:(?P<id>\d+)/)?$' => 'PhabricatorFileMacroEditController',

View file

@ -181,16 +181,48 @@ class AphrontRequest {
}
final public function setCookie($name, $value, $expire = null) {
// Ensure cookies are only set on the configured domain.
$base_uri = PhabricatorEnv::getEnvConfig('phabricator.base-uri');
$base_uri = new PhutilURI($base_uri);
$base_domain = $base_uri->getDomain();
$base_protocol = $base_uri->getProtocol();
$actual_host = $this->getHost();
if ($base_domain != $actual_host) {
throw new Exception(
"This install of Phabricator is configured as '{$base_domain}' but ".
"you are accessing it via '{$actual_host}'. Access Phabricator via ".
"the primary configured domain.");
}
if ($expire === null) {
$expire = time() + (60 * 60 * 24 * 365 * 5);
}
if ($value == '') {
// NOTE: If we're clearing the cookie, also clear it on the entire
// domain. This allows us to clear older cookies which we didn't scope
// as tightly.
setcookie(
$name,
$value,
$expire,
$path = '/',
$domain = '',
$secure = ($base_protocol == 'https'),
$http_only = true);
}
setcookie(
$name,
$value,
$expire,
$path = '/',
$domain = '',
$secure = false,
$base_domain,
$secure = ($base_protocol == 'https'),
$http_only = true);
}

View file

@ -7,6 +7,7 @@
phutil_require_module('phabricator', 'aphront/exception/csrf');
phutil_require_module('phabricator', 'infrastructure/env');
phutil_require_module('phutil', 'parser/uri');
phutil_require_module('phutil', 'utils');

View file

@ -0,0 +1,68 @@
<?php
/*
* Copyright 2011 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
class PhabricatorFileAltViewController extends PhabricatorFileController {
private $phid;
private $key;
public function willProcessRequest(array $data) {
$this->phid = $data['phid'];
$this->key = $data['key'];
}
public function shouldRequireLogin() {
return false;
}
public function processRequest() {
$alt = PhabricatorEnv::getEnvConfig('security.alternate-file-domain');
if (!$alt) {
return new Aphront400Response();
}
$request = $this->getRequest();
$alt_domain = id(new PhutilURI($alt))->getDomain();
if ($alt_domain != $request->getHost()) {
return new Aphront400Response();
}
$file = id(new PhabricatorFile())->loadOneWhere(
'phid = %s',
$this->phid);
if (!$file) {
return new Aphront404Response();
}
if (!$file->validateSecretKey($this->key)) {
return new Aphront404Response();
}
// It's safe to bypass view restrictions because we know we are being served
// off an alternate domain which we will not set cookies on.
$data = $file->loadFileData();
$response = new AphrontFileResponse();
$response->setContent($data);
$response->setCacheDurationInSeconds(60 * 60 * 24 * 30);
return $response;
}
}

View file

@ -0,0 +1,20 @@
<?php
/**
* This file is automatically generated. Lint this module to rebuild it.
* @generated
*/
phutil_require_module('phabricator', 'aphront/response/400');
phutil_require_module('phabricator', 'aphront/response/404');
phutil_require_module('phabricator', 'aphront/response/file');
phutil_require_module('phabricator', 'applications/files/controller/base');
phutil_require_module('phabricator', 'applications/files/storage/file');
phutil_require_module('phabricator', 'infrastructure/env');
phutil_require_module('phutil', 'parser/uri');
phutil_require_module('phutil', 'utils');
phutil_require_source('PhabricatorFileAltViewController.php');

View file

@ -75,7 +75,7 @@ class PhabricatorFileListController extends PhabricatorFileController {
'a',
array(
'class' => 'small button grey',
'href' => '/file/view/'.$file->getPHID().'/',
'href' => $file->getViewURI(),
),
'View');
} else {

View file

@ -71,6 +71,18 @@ class PhabricatorFileViewController extends PhabricatorFileController {
$mime_type = $file->getViewableMimeType();
}
// If an alternate file domain is configured, forbid all views which
// don't originate from it.
if (!$download) {
$alt = PhabricatorEnv::getEnvConfig('security.alternate-file-domain');
if ($alt) {
$domain = id(new PhutilURI($alt))->getDomain();
if ($domain != $request->getHost()) {
return new Aphront400Response();
}
}
}
$response->setMimeType($mime_type);
if ($download) {
@ -98,7 +110,7 @@ class PhabricatorFileViewController extends PhabricatorFileController {
$form = new AphrontFormView();
if ($file->isViewableInBrowser()) {
$form->setAction('/file/view/'.$file->getPHID().'/');
$form->setAction($file->getViewURI());
$button_name = 'View File';
} else {
$form->setAction('/file/download/'.$file->getPHID().'/');

View file

@ -15,6 +15,7 @@ phutil_require_module('phabricator', 'applications/files/storage/file');
phutil_require_module('phabricator', 'applications/files/storage/transformed');
phutil_require_module('phabricator', 'applications/files/uri');
phutil_require_module('phabricator', 'applications/people/storage/user');
phutil_require_module('phabricator', 'infrastructure/env');
phutil_require_module('phabricator', 'view/control/table');
phutil_require_module('phabricator', 'view/form/base');
phutil_require_module('phabricator', 'view/form/control/static');
@ -23,6 +24,7 @@ phutil_require_module('phabricator', 'view/layout/panel');
phutil_require_module('phabricator', 'view/utils');
phutil_require_module('phutil', 'markup');
phutil_require_module('phutil', 'parser/uri');
phutil_require_module('phutil', 'utils');

View file

@ -216,7 +216,16 @@ class PhabricatorFile extends PhabricatorFileDAO {
}
public function getViewURI() {
return PhabricatorFileURI::getViewURIForPHID($this->getPHID());
$alt = PhabricatorEnv::getEnvConfig('security.alternate-file-domain');
if ($alt) {
$path = '/file/alt/'.$this->generateSecretKey().'/'.$this->getPHID().'/';
$uri = new PhutilURI($alt);
$uri->setPath($path);
return (string)$uri;
} else {
return '/file/view/'.$this->getPHID().'/';
}
}
public function getInfoURI() {
@ -302,4 +311,14 @@ class PhabricatorFile extends PhabricatorFileDAO {
return idx($mime_map, $mime_type);
}
public function validateSecretKey($key) {
return ($key == $this->generateSecretKey());
}
private function generateSecretKey() {
$file_key = PhabricatorEnv::getEnvConfig('phabricator.file-key');
$hash = sha1($this->phid.$this->storageHandle.$file_key);
return substr($hash, 0, 20);
}
}

View file

@ -8,7 +8,6 @@
phutil_require_module('phabricator', 'applications/files/exception/upload');
phutil_require_module('phabricator', 'applications/files/storage/base');
phutil_require_module('phabricator', 'applications/files/uri');
phutil_require_module('phabricator', 'applications/phid/constants');
phutil_require_module('phabricator', 'applications/phid/storage/phid');
phutil_require_module('phabricator', 'infrastructure/env');

View file

@ -19,7 +19,18 @@
final class PhabricatorFileURI {
public static function getViewURIForPHID($phid) {
return '/file/view/'.$phid.'/';
// TODO: Get rid of this class, the advent of the applet attack makes the
// tiny optimization it represented effectively obsolete.
$file = id(new PhabricatorFile())->loadOneWhere(
'phid = %s',
$phid);
if ($file) {
return $file->getViewURI();
}
return null;
}
}

View file

@ -6,5 +6,9 @@
phutil_require_module('phabricator', 'applications/files/storage/file');
phutil_require_module('phutil', 'utils');
phutil_require_source('PhabricatorFileURI.php');

View file

@ -114,6 +114,14 @@ class PhabricatorSetup {
self::write(" okay 'open_basedir' is not set.\n");
}
if (!PhabricatorEnv::getEnvConfig('security.alternate-file-domain')) {
self::write(
"[WARN] You have not configured 'security.alternate-file-domain'. ".
"This may make your installation vulnerable to attack. Make sure ".
"you read the documentation for this parameter and understand the ".
"consequences of leaving it unconfigured.\n");
}
self::write("[OKAY] Core configuration OKAY.\n");
self::writeHeader("REQUIRED PHP EXTENSIONS");