File swift-tempurl-timing.patch of Package openstack-swift

commit 6c378b4b65524ea3b485c47d829ed0aebbdb86c0
Author: Samuel Merritt <sam@swiftstack.com>
Date:   Fri Jan 3 09:26:11 2014 -0800

    Backported tempurl const time compare for 1.10.0
    
    Change-Id: I6db8f9a568dab8403ed74a83ba0c9548f06425e1

diff --git a/swift/common/middleware/tempurl.py b/swift/common/middleware/tempurl.py
index ffc1431..ae2f4a1 100644
--- a/swift/common/middleware/tempurl.py
+++ b/swift/common/middleware/tempurl.py
@@ -98,7 +98,7 @@ from urlparse import parse_qs
 
 from swift.proxy.controllers.base import get_account_info
 from swift.common.swob import HeaderKeyDict
-from swift.common.utils import split_path
+from swift.common.utils import split_path, streq_const_time
 
 
 #: Default headers to remove from incoming requests. Simply a whitespace
@@ -267,17 +267,20 @@ class TempURL(object):
         if not keys:
             return self._invalid(env, start_response)
         if env['REQUEST_METHOD'] == 'HEAD':
-            hmac_vals = self._get_hmacs(env, temp_url_expires, keys,
-                                        request_method='GET')
-            if temp_url_sig not in hmac_vals:
-                hmac_vals = self._get_hmacs(env, temp_url_expires, keys,
-                                            request_method='PUT')
-                if temp_url_sig not in hmac_vals:
-                    return self._invalid(env, start_response)
+            hmac_vals = (self._get_hmacs(env, temp_url_expires, keys,
+                                         request_method='GET') +
+                         self._get_hmacs(env, temp_url_expires, keys,
+                                         request_method='PUT'))
         else:
             hmac_vals = self._get_hmacs(env, temp_url_expires, keys)
-            if temp_url_sig not in hmac_vals:
-                return self._invalid(env, start_response)
+
+        # While it's true that any() will short-circuit, this doesn't affect
+        # the timing-attack resistance since the only way this will
+        # short-circuit is when a valid signature is passed in.
+        is_valid_hmac = any(streq_const_time(temp_url_sig, h)
+                            for h in hmac_vals)
+        if not is_valid_hmac:
+            return self._invalid(env, start_response)
         self._clean_incoming_headers(env)
         env['swift.authorize'] = lambda req: None
         env['swift.authorize_override'] = True