BF: fix infinite recursion case in Action.substituteRecursiveTags

fail2ban/server/action.py

@@ -276,19 +276,27 @@ class Action:
 		for tag, value in tags.iteritems():
 			value = str(value)
 			m = t.search(value)
+			done = []
+			#logSys.log(5, 'TAG: %s, value: %s' % (tag, value))
 			while m:
-				if m.group(1) == tag:
+				found_tag = m.group(1)
+				#logSys.log(5, 'found: %s' % found_tag)
+				if found_tag == tag or found_tag in done:
 					# recursive definitions are bad
+					#logSys.log(5, 'recursion fail')
 					return False
 				else:
-					if tags.has_key(m.group(1)):
-						value = value[0:m.start()] + tags[m.group(1)] + value[m.end():]
+					if tags.has_key(found_tag):
+						value = value[0:m.start()] + tags[found_tag] + value[m.end():]
+						#logSys.log(5, 'value now: %s' % value)
+						done.append(found_tag)
 						m = t.search(value, m.start())
 					else:
 						# Missing tags are ok so we just continue on searching.
 						# cInfo can contain aInfo elements like <HOST> and valid shell
 						# constructs like <STDIN>.
 						m = t.search(value, m.start() + 1)
+			#logSys.log(5, 'TAG: %s, newvalue: %s' % (tag, value))
 			tags[tag] = value
 		return tags
 	substituteRecursiveTags = staticmethod(substituteRecursiveTags)

fail2ban/tests/actiontestcase.py

@@ -58,6 +58,9 @@ class ExecuteAction(LogCaptureTestCase):
 		self.assertFalse(Action.substituteRecursiveTags({'A': '<A>'}))
 		self.assertFalse(Action.substituteRecursiveTags({'A': '<B>', 'B': '<A>'}))
 		self.assertFalse(Action.substituteRecursiveTags({'A': '<B>', 'B': '<C>', 'C': '<A>'}))
+		# part recursion
+		self.assertFalse(Action.substituteRecursiveTags({'A': 'to=<B> fromip=<IP>', 'C': '<B>', 'B': '<C>', 'D': ''}))
+		self.assertFalse(Action.substituteRecursiveTags({'failregex': 'to=<honeypot> fromip=<IP>', 'sweet': '<honeypot>', 'honeypot': '<sweet>', 'ignoreregex': ''}))
 		# missing tags are ok
 		self.assertEqual(Action.substituteRecursiveTags({'A': '<C>'}), {'A': '<C>'})
 		self.assertEqual(Action.substituteRecursiveTags({'A': '<C> <D> <X>','X':'fun'}), {'A': '<C> <D> fun', 'X':'fun'})