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Code Issues Releases Wiki Activity

substituteRecursiveTags: more precise self- or cyclic-recursion prevention (don't clear replacement counts of tags, rather consider replacement count by tax X in tag Y)

pull/2713/head
sebres 2020-08-26 12:05:20 +02:00
parent 81fb28e146
commit 5a2cc4e1c5
2 changed files with 9 additions and 7 deletions
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14
fail2ban/helpers.py
View File

@ -398,8 +398,8 @@ def splitWithOptions(option):
# tags (<tag>) in tagged options.
#
# max tag replacement count:
MAX_TAG_REPLACE_COUNT = 10
# max tag replacement count (considering tag X in tag Y repeat):
MAX_TAG_REPLACE_COUNT = 25
# compiled RE for tag name (replacement name)
TAG_CRE = re.compile(r'<([^ <>]+)>')
@ -433,6 +433,7 @@ def substituteRecursiveTags(inptags, conditional='',
done = set()
noRecRepl = hasattr(tags, "getRawItem")
# repeat substitution while embedded-recursive (repFlag is True)
repCounts = {}
while True:
repFlag = False
# substitute each value:
@ -444,7 +445,7 @@ def substituteRecursiveTags(inptags, conditional='',
value = orgval = uni_string(tags[tag])
# search and replace all tags within value, that can be interpolated using other tags:
m = tre_search(value)
refCounts = {}
rplc = repCounts.get(tag, {})
#logSys.log(5, 'TAG: %s, value: %s' % (tag, value))
while m:
# found replacement tag:
@ -454,13 +455,13 @@ def substituteRecursiveTags(inptags, conditional='',
m = tre_search(value, m.end())
continue
#logSys.log(5, 'found: %s' % rtag)
if rtag == tag or refCounts.get(rtag, 1) > MAX_TAG_REPLACE_COUNT:
if rtag == tag or rplc.get(rtag, 1) > MAX_TAG_REPLACE_COUNT:
# recursive definitions are bad
#logSys.log(5, 'recursion fail tag: %s value: %s' % (tag, value) )
raise ValueError(
"properties contain self referencing definitions "
"and cannot be resolved, fail tag: %s, found: %s in %s, value: %s" %
(tag, rtag, refCounts, value))
(tag, rtag, rplc, value))
repl = None
if conditional:
repl = tags.get(rtag + '?' + conditional)
@ -480,7 +481,7 @@ def substituteRecursiveTags(inptags, conditional='',
value = value.replace('<%s>' % rtag, repl)
#logSys.log(5, 'value now: %s' % value)
# increment reference count:
refCounts[rtag] = refCounts.get(rtag, 0) + 1
rplc[rtag] = rplc.get(rtag, 0) + 1
# the next match for replace:
m = tre_search(value, m.start())
#logSys.log(5, 'TAG: %s, newvalue: %s' % (tag, value))
@ -488,6 +489,7 @@ def substituteRecursiveTags(inptags, conditional='',
if orgval != value:
# check still contains any tag - should be repeated (possible embedded-recursive substitution):
if tre_search(value):
repCounts[tag] = rplc
repFlag = True
# copy return tags dict to prevent modifying of inptags:
if id(tags) == id(inptags):

2
fail2ban/tests/actiontestcase.py
View File

@ -252,7 +252,7 @@ class CommandActionTest(LogCaptureTestCase):
delattr(self.__action, 'ac')
# produce self-referencing query except:
self.assertRaisesRegexp(ValueError, r"possible self referencing definitions in query",
lambda: self.__action.replaceTag("<x<x<x<x<x<x<x<x<x<x<x<x<x<x<x<x<x<x<x<x<x>>>>>>>>>>>>>>>>>>>>>",
lambda: self.__action.replaceTag("<x"*30+">"*30,
self.__action._properties, conditional="family=inet6")
)