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Code Issues Releases Wiki Activity

Improve granluarity and defaults of security.allow-outbound-http

Browse source 
Summary:
Ref T6755. This is a partial fix, but:

  - Allow netblocks to be blacklisted instead of making the feature all-or-nothing.
  - Default to disallow requests to all reserved private/local/special IP blocks. This should generally be a "safe" setting.
  - Explain the risks better.
  - Improve the errors rasied by Macro when failing.
  - Removed `security.allow-outbound-http`, as it is superseded by this setting and is somewhat misleading.
    - We still make outbound HTTP requests to OAuth.
    - We still make outbound HTTP requests for repositories.

From a technical perspective:

  - Separate URIs that are safe to link to or redirect to (basically, not "javascript://") from URIs that are safe to fetch (nothing in a private block).
  - Add the default blacklist.
  - Be more careful with response data in Macro fetching, and don't let the user see it if it isn't ultimately valid.

Additionally:

  - I want to do this check before pulling repositories, but that's enough of a mess that it should go in a separate diff.
  - The future implementation of T4190 needs to perform the fetch check.

Test Plan:
  - Fetched a valid macro.
  - Fetched a non-image, verified it didn't result in a viewable file.
  - Fetched a private-ip-space image, got an error.
  - Fetched a 404, got a useful-enough error without additional revealing response content (which is usually HTML anyway and not useful).
  - Fetched a bad protocol, got an error.
  - Linked to a local resource, a phriction page, a valid remote site, all worked.
  - Linked to private IP space, which worked fine (we want to let you link and redierect to other private services, just not fetch them).
  - Added and executed unit tests.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T6755

Differential Revision: https://secure.phabricator.com/D12136
This commit is contained in:
epriestley 2015-03-23 10:44:03 -07:00
parent 5f7b7f24d6
commit 1c32c9b965
13 changed files with 308 additions and 79 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
src/aphront/response/AphrontRedirectResponse.php
View file

@ -127,7 +127,7 @@ class AphrontRedirectResponse extends AphrontResponse {
}
// Check that it's a valid remote resource.
if (!PhabricatorEnv::isValidRemoteWebResource($uri)) {
if (!PhabricatorEnv::isValidURIForLink($uri)) {
throw new Exception(
pht(
'Refusing to redirect to external URI "%s". This URI '.
@ -148,7 +148,7 @@ class AphrontRedirectResponse extends AphrontResponse {
}
// If this is a local resource, it must be a valid local resource.
if (!PhabricatorEnv::isValidLocalWebResource($uri)) {
if (!PhabricatorEnv::isValidLocalURIForLink($uri)) {
throw new Exception(
pht(
'Refusing to redirect to local resource "%s". This URI is not '.

2
src/applications/auth/controller/PhabricatorAuthFinishController.php
View file

@ -74,7 +74,7 @@ final class PhabricatorAuthFinishController
$request->clearCookie(PhabricatorCookies::COOKIE_NEXTURI);
$request->clearCookie(PhabricatorCookies::COOKIE_HISEC);
if (!PhabricatorEnv::isValidLocalWebResource($next)) {
if (!PhabricatorEnv::isValidLocalURIForLink($next)) {
$next = '/';
}

2
src/applications/auth/view/PhabricatorAuthAccountView.php
View file

@ -71,7 +71,7 @@ final class PhabricatorAuthAccountView extends AphrontView {
// Make sure we don't link a "javascript:" URI if a user somehow
// managed to get one here.
if (PhabricatorEnv::isValidRemoteWebResource($account_uri)) {
if (PhabricatorEnv::isValidRemoteURIForLink($account_uri)) {
$account_uri = phutil_tag(
'a',
array(

3
src/applications/config/check/PhabricatorExtraConfigSetupCheck.php
View file

@ -217,6 +217,9 @@ final class PhabricatorExtraConfigSetupCheck extends PhabricatorSetupCheck {
'storage.upload-size-limit' => pht(
'Phabricator now supports arbitrarily large files. Consult the '.
'documentation for configuration details.'),
'security.allow-outbound-http' => pht(
'This option has been replaced with the more granular option '.
'`security.outbound-blacklist`.'),
);
return $ancient_config;

51
src/applications/config/option/PhabricatorSecurityConfigOptions.php
View file

@ -25,6 +25,26 @@ final class PhabricatorSecurityConfigOptions
$doc_href = PhabricatorEnv::getDoclink('Configuring a File Domain');
$doc_name = pht('Configuration Guide: Configuring a File Domain');
// This is all of the IANA special/reserved blocks in IPv4 space.
$default_address_blacklist = array(
'0.0.0.0/8',
'10.0.0.0/8',
'100.64.0.0/10',
'127.0.0.0/8',
'169.254.0.0/16',
'172.16.0.0/12',
'192.0.0.0/24',
'192.0.2.0/24',
'192.88.99.0/24',
'192.168.0.0/16',
'198.18.0.0/15',
'198.51.100.0/24',
'203.0.113.0/24',
'224.0.0.0/4',
'240.0.0.0/4',
'255.255.255.255/32',
);
return array(
$this->newOption('security.alternate-file-domain', 'string', null)
->setLocked(true)
@ -210,19 +230,32 @@ final class PhabricatorSecurityConfigOptions
"inline. This has mild security implications (you'll leak ".
"referrers to YouTube) and is pretty silly (but sort of ".
"awesome).")),
$this->newOption('security.allow-outbound-http', 'bool', true)
->setBoolOptions(
array(
pht('Allow'),
pht('Disallow'),
))
$this->newOption(
'security.outbound-blacklist',
'list<string>',
$default_address_blacklist)
->setLocked(true)
->setSummary(
pht('Allow outbound HTTP requests.'))
pht(
'Blacklist subnets to prevent user-initiated outbound '.
'requests.'))
->setDescription(
pht(
'If you enable this, you are allowing Phabricator to '.
'potentially make requests to external servers.')),
'Phabricator users can make requests to other services from '.
'the Phabricator host in some circumstances (for example, by '.
'creating a repository with a remote URL or having Phabricator '.
'fetch an image from a remote server).'.
"\n\n".
'This may represent a security vulnerability if services on '.
'the same subnet will accept commands or reveal private '.
'information over unauthenticated HTTP GET, based on the source '.
'IP address. In particular, all hosts in EC2 have access to '.
'such a service.'.
"\n\n".
'This option defines a list of netblocks which Phabricator '.
'will decline to connect to. Generally, you should list all '.
'private IP space here.'))
->addExample(array('0.0.0.0/0'), pht('No Outbound Requests')),
$this->newOption('security.strict-transport-security', 'bool', false)
->setLocked(true)
->setBoolOptions(

23
src/applications/files/storage/PhabricatorFile.php
View file

@ -452,25 +452,14 @@ final class PhabricatorFile extends PhabricatorFileDAO
public static function newFromFileDownload($uri, array $params = array()) {
// Make sure we're allowed to make a request first
if (!PhabricatorEnv::getEnvConfig('security.allow-outbound-http')) {
throw new Exception('Outbound HTTP requests are disabled!');
}
$uri = new PhutilURI($uri);
$protocol = $uri->getProtocol();
switch ($protocol) {
case 'http':
case 'https':
break;
default:
// Make sure we are not accessing any file:// URIs or similar.
return null;
}
PhabricatorEnv::requireValidRemoteURIForFetch(
$uri,
array(
'http',
'https',
));
$timeout = 5;
list($file_data) = id(new HTTPSFuture($uri))
->setTimeout($timeout)
->resolvex();

39
src/applications/macro/controller/PhabricatorMacroEditController.php
View file

@ -33,7 +33,6 @@ final class PhabricatorMacroEditController extends PhabricatorMacroController {
$e_name = true;
$e_file = null;
$file = null;
$can_fetch = PhabricatorEnv::getEnvConfig('security.allow-outbound-http');
if ($request->isFormPost()) {
$original = clone $macro;
@ -57,6 +56,10 @@ final class PhabricatorMacroEditController extends PhabricatorMacroController {
}
}
$uri = $request->getStr('url');
$engine = new PhabricatorDestructionEngine();
$file = null;
if ($request->getFileExists('file')) {
$file = PhabricatorFile::newFromPHPUpload(
@ -67,18 +70,40 @@ final class PhabricatorMacroEditController extends PhabricatorMacroController {
'isExplicitUpload' => true,
'canCDN' => true,
));
} else if ($request->getStr('url') && $can_fetch) {
} else if ($uri) {
try {
$file = PhabricatorFile::newFromFileDownload(
$request->getStr('url'),
$uri,
array(
'name' => $request->getStr('name'),
'authorPHID' => $user->getPHID(),
'viewPolicy' => PhabricatorPolicies::POLICY_NOONE,
'isExplicitUpload' => true,
'canCDN' => true,
));
if (!$file->isViewableInBrowser()) {
$mime_type = $file->getMimeType();
$engine->destroyObject($file);
$file = null;
throw new Exception(
pht(
'The URI "%s" does not correspond to a valid image file, got '.
'a file with MIME type "%s". You must specify the URI of a '.
'valid image file.',
$uri,
$mime_type));
} else {
$file
->setAuthorPHID($user->getPHID())
->save();
}
} catch (HTTPFutureHTTPResponseStatus $status) {
$errors[] = pht(
'The URI "%s" could not be loaded, got %s error.',
$uri,
$status->getStatusCode());
} catch (Exception $ex) {
$errors[] = pht('Could not fetch URL: %s', $ex->getMessage());
$errors[] = $ex->getMessage();
}
} else if ($request->getStr('phid')) {
$file = id(new PhabricatorFileQuery())
@ -175,14 +200,12 @@ final class PhabricatorMacroEditController extends PhabricatorMacroController {
$other_label = pht('File');
}
if ($can_fetch) {
$form->appendChild(
id(new AphrontFormTextControl())
->setLabel(pht('URL'))
->setName('url')
->setValue($request->getStr('url'))
->setError($request->getFileExists('file') ? false : $e_file));
}
$form->appendChild(
id(new AphrontFormFileControl())
@ -226,13 +249,11 @@ final class PhabricatorMacroEditController extends PhabricatorMacroController {
->setEncType('multipart/form-data')
->setUser($request->getUser());
if ($can_fetch) {
$upload_form->appendChild(
id(new AphrontFormTextControl())
->setLabel(pht('URL'))
->setName('url')
->setValue($request->getStr('url')));
}
$upload_form
->appendChild(

2
src/applications/mailinglists/controller/PhabricatorMailingListsEditController.php
View file

@ -54,7 +54,7 @@ final class PhabricatorMailingListsEditController
}
if ($list->getURI()) {
if (!PhabricatorEnv::isValidWebResource($list->getURI())) {
if (!PhabricatorEnv::isValidRemoteURIForLink($list->getURI())) {
$e_uri = pht('Invalid');
$errors[] = pht('Mailing list URI must point to a valid web page.');
}

2
src/applications/oauthserver/PhabricatorOAuthServer.php
View file

@ -198,7 +198,7 @@ final class PhabricatorOAuthServer {
* for details on what makes a given redirect URI "valid".
*/
public function validateRedirectURI(PhutilURI $uri) {
if (!PhabricatorEnv::isValidRemoteWebResource($uri)) {
if (!PhabricatorEnv::isValidRemoteURIForLink($uri)) {
return false;
}

182
src/infrastructure/env/PhabricatorEnv.php vendored
View file

@ -563,11 +563,11 @@ final class PhabricatorEnv {
/**
* Detect if a URI satisfies either @{method:isValidLocalWebResource} or
* @{method:isValidRemoteWebResource}, i.e. is a page on this server or the
* Detect if a URI satisfies either @{method:isValidLocalURIForLink} or
* @{method:isValidRemoteURIForLink}, i.e. is a page on this server or the
* URI of some other resource which has a valid protocol. This rejects
* garbage URIs and URIs with protocols which do not appear in the
* ##uri.allowed-protocols## configuration, notably 'javascript:' URIs.
* `uri.allowed-protocols` configuration, notably 'javascript:' URIs.
*
* NOTE: This method is generally intended to reject URIs which it may be
* unsafe to put in an "href" link attribute.
@ -576,9 +576,9 @@ final class PhabricatorEnv {
* @return bool True if the URI identifies a web resource.
* @task uri
*/
public static function isValidWebResource($uri) {
return self::isValidLocalWebResource($uri) ||
self::isValidRemoteWebResource($uri);
public static function isValidURIForLink($uri) {
return self::isValidLocalURIForLink($uri) ||
self::isValidRemoteURIForLink($uri);
}
@ -592,7 +592,7 @@ final class PhabricatorEnv {
* @return bool True if the URI identifies a local page.
* @task uri
*/
public static function isValidLocalWebResource($uri) {
public static function isValidLocalURIForLink($uri) {
$uri = (string)$uri;
if (!strlen($uri)) {
@ -628,27 +628,167 @@ final class PhabricatorEnv {
/**
* Detect if a URI identifies some valid remote resource.
* Detect if a URI identifies some valid linkable remote resource.
*
* @param string URI to test.
* @return bool True if a URI idenfies a remote resource with an allowed
* protocol.
* @task uri
*/
public static function isValidRemoteWebResource($uri) {
$uri = (string)$uri;
$proto = id(new PhutilURI($uri))->getProtocol();
if (!$proto) {
return false;
}
$allowed = self::getEnvConfig('uri.allowed-protocols');
if (empty($allowed[$proto])) {
return false;
}
public static function isValidRemoteURIForLink($uri) {
try {
self::requireValidRemoteURIForLink($uri);
return true;
} catch (Exception $ex) {
return false;
}
}
/**
* Detect if a URI identifies a valid linkable remote resource, throwing a
* detailed message if it does not.
*
* A valid linkable remote resource can be safely linked or redirected to.
* This is primarily a protocol whitelist check.
*
* @param string URI to test.
* @return void
* @task uri
*/
public static function requireValidRemoteURIForLink($uri) {
$uri = new PhutilURI($uri);
$proto = $uri->getProtocol();
if (!strlen($proto)) {
throw new Exception(
pht(
'URI "%s" is not a valid linkable resource. A valid linkable '.
'resource URI must specify a protocol.',
$uri));
}
$protocols = self::getEnvConfig('uri.allowed-protocols');
if (!isset($protocols[$proto])) {
throw new Exception(
pht(
'URI "%s" is not a valid linkable resource. A valid linkable '.
'resource URI must use one of these protocols: %s.',
$uri,
implode(', ', array_keys($protocols))));
}
$domain = $uri->getDomain();
if (!strlen($domain)) {
throw new Exception(
pht(
'URI "%s" is not a valid linkable resource. A valid linkable '.
'resource URI must specify a domain.',
$uri));
}
}
/**
* Detect if a URI identifies a valid fetchable remote resource.
*
* @param string URI to test.
* @param list<string> Allowed protocols.
* @return bool True if the URI is a valid fetchable remote resource.
* @task uri
*/
public static function isValidRemoteURIForFetch($uri, array $protocols) {
try {
self::requireValidRemoteURIForFetch($uri, $protocols);
return true;
} catch (Exception $ex) {
return false;
}
}
/**
* Detect if a URI identifies a valid fetchable remote resource, throwing
* a detailed message if it does not.
*
* A valid fetchable remote resource can be safely fetched using a request
* originating on this server. This is a primarily an address check against
* the outbound address blacklist.
*
* @param string URI to test.
* @param list<string> Allowed protocols.
* @return void
* @task uri
*/
public static function requireValidRemoteURIForFetch(
$uri,
array $protocols) {
$uri = new PhutilURI($uri);
$proto = $uri->getProtocol();
if (!strlen($proto)) {
throw new Exception(
pht(
'URI "%s" is not a valid fetchable resource. A valid fetchable '.
'resource URI must specify a protocol.',
$uri));
}
$protocols = array_fuse($protocols);
if (!isset($protocols[$proto])) {
throw new Exception(
pht(
'URI "%s" is not a valid fetchable resource. A valid fetchable '.
'resource URI must use one of these protocols: %s.',
$uri,
implode(', ', array_keys($protocols))));
}
$domain = $uri->getDomain();
if (!strlen($domain)) {
throw new Exception(
pht(
'URI "%s" is not a valid fetchable resource. A valid fetchable '.
'resource URI must specify a domain.',
$uri));
}
$addresses = gethostbynamel($domain);
if (!$addresses) {
throw new Exception(
pht(
'URI "%s" is not a valid fetchable resource. The domain "%s" could '.
'not be resolved.',
$uri,
$domain));
}
foreach ($addresses as $address) {
if (self::isBlacklistedOutboundAddress($address)) {
throw new Exception(
pht(
'URI "%s" is not a valid fetchable resource. The domain "%s" '.
'resolves to the address "%s", which is blacklisted for '.
'outbound requests.',
$uri,
$domain,
$address));
}
}
}
/**
* Determine if an IP address is in the outbound address blacklist.
*
* @param string IP address.
* @return bool True if the address is blacklisted.
*/
public static function isBlacklistedOutboundAddress($address) {
$blacklist = self::getEnvConfig('security.outbound-blacklist');
return PhutilCIDRList::newList($blacklist)->containsAddress($address);
}
public static function isClusterRemoteAddress() {

53
src/infrastructure/env/__tests__/PhabricatorEnvTestCase.php vendored
View file

@ -2,7 +2,7 @@
final class PhabricatorEnvTestCase extends PhabricatorTestCase {
public function testLocalWebResource() {
public function testLocalURIForLink() {
$map = array(
'/' => true,
'/D123' => true,
@ -19,23 +19,66 @@ final class PhabricatorEnvTestCase extends PhabricatorTestCase {
foreach ($map as $uri => $expect) {
$this->assertEqual(
$expect,
PhabricatorEnv::isValidLocalWebResource($uri),
PhabricatorEnv::isValidLocalURIForLink($uri),
"Valid local resource: {$uri}");
}
}
public function testRemoteWebResource() {
public function testRemoteURIForLink() {
$map = array(
'http://example.com/' => true,
'derp://example.com/' => false,
'javascript:alert(1)' => false,
'http://127.0.0.1/' => true,
'http://169.254.169.254/latest/meta-data/hostname' => true,
);
foreach ($map as $uri => $expect) {
$this->assertEqual(
$expect,
PhabricatorEnv::isValidRemoteWebResource($uri),
"Valid remote resource: {$uri}");
PhabricatorEnv::isValidRemoteURIForLink($uri),
"Valid linkable remote URI: {$uri}");
}
}
public function testRemoteURIForFetch() {
$map = array(
'http://example.com/' => true,
// No domain or protocol.
'' => false,
// No domain.
'http://' => false,
// No protocol.
'evil.com' => false,
// No protocol.
'//evil.com' => false,
// Bad protocol.
'javascript://evil.com/' => false,
'file:///etc/shadow' => false,
// Unresolvable hostname.
'http://u1VcxwUp368SIFzl7rkWWg23KM5JPB2kTHHngxjXCQc.zzz/' => false,
// Domains explicitly in blacklisted IP space.
'http://127.0.0.1/' => false,
'http://169.254.169.254/latest/meta-data/hostname' => false,
// Domain resolves into blacklisted IP space.
'http://localhost/' => false,
);
$protocols = array('http', 'https');
foreach ($map as $uri => $expect) {
$this->assertEqual(
$expect,
PhabricatorEnv::isValidRemoteURIForFetch($uri, $protocols),
"Valid fetchable remote URI: {$uri}");
}
}

2
src/infrastructure/markup/rule/PhabricatorNavigationRemarkupRule.php
View file

@ -71,7 +71,7 @@ final class PhabricatorNavigationRemarkupRule extends PhutilRemarkupRule {
}
if ($item['href'] !== null) {
if (PhabricatorEnv::isValidWebResource($item['href'])) {
if (PhabricatorEnv::isValidRemoteURIForLink($item['href'])) {
$tag->setHref($item['href']);
$tag->setExternal(true);
}

2
src/view/page/PhabricatorStandardPageView.php
View file

@ -562,7 +562,7 @@ final class PhabricatorStandardPageView extends PhabricatorBarePageView {
$name = idx($item, 'name', pht('Unnamed Footer Item'));
$href = idx($item, 'href');
if (!PhabricatorEnv::isValidWebResource($href)) {
if (!PhabricatorEnv::isValidURIForLink($href)) {
$href = null;
}