# Copyright 2016, Tresys Technology, LLC
#
# SPDX-License-Identifier: LGPL-2.1-only
#
from contextlib import suppress
from typing import Iterable, List, Optional, Tuple
from .exception import InvalidPermission, NoCommon
from .policyrep import Level, ObjClass, SELinuxPolicy
def match_regex(obj, criteria, regex: bool) -> bool:
"""
Match the object with optional regular expression.
Parameters:
obj The object to match.
criteria The criteria to match.
regex If regular expression matching should be used.
"""
if regex:
return bool(criteria.search(str(obj)))
else:
return obj == criteria
def match_set(obj, criteria, equal: bool) -> bool:
"""
Match the object (a set) with optional set equality.
Parameters:
obj The object to match. (a set)
criteria The criteria to match. (a set)
equal If set equality should be used. Otherwise
any set intersection will match.
"""
if equal:
return obj == criteria
else:
return bool(obj.intersection(criteria))
def match_in_set(obj, criteria, regex: bool) -> bool:
"""
Match if the criteria is in the list, with optional
regular expression matching.
Parameters:
obj The object to match.
criteria The criteria to match.
regex If regular expression matching should be used.
"""
if regex:
return bool([m for m in obj if criteria.search(str(m))])
else:
return criteria in obj
def match_indirect_regex(obj, criteria, indirect: bool, regex: bool) -> bool:
"""
Match the object with optional regular expression and indirection.
Parameters:
obj The object to match.
criteria The criteria to match.
regex If regular expression matching should be used.
indirect If object indirection should be used, e.g.
expanding an attribute.
"""
if indirect:
if regex:
return bool([o for o in obj.expand() if criteria.search(str(o))])
else:
return bool(set(criteria.expand()).intersection(obj.expand()))
else:
return match_regex(obj, criteria, regex)
def match_regex_or_set(obj, criteria, equal: bool, regex: bool) -> bool:
"""
Match the object (a set) with either set comparisons
(equality or intersection) or by regex matching of the
set members. Regular expression matching will override
the set equality option.
Parameters:
obj The object to match. (a set)
criteria The criteria to match.
equal If set equality should be used. Otherwise
any set intersection will match. Ignored
if regular expression matching is used.
regex If regular expression matching should be used.
"""
if regex:
return bool([m for m in obj if criteria.search(str(m))])
else:
return match_set(obj, set(criteria), equal)
def match_range(obj, criteria, subset: bool, overlap: bool, superset: bool, proper: bool) -> bool:
"""
Match ranges of objects.
obj An object with attributes named "low" and "high", representing the range.
criteria An object with attributes named "low" and "high", representing the criteria.
subset If true, the criteria will match if it is a subset obj's range.
overlap If true, the criteria will match if it overlaps any of the obj's range.
superset If true, the criteria will match if it is a superset of the obj's range.
proper If true, use proper superset/subset operations.
No effect if not using set operations.
"""
if overlap:
return ((obj.low <= criteria.low <= obj.high) or (
obj.low <= criteria.high <= obj.high) or (
criteria.low <= obj.low and obj.high <= criteria.high))
elif subset:
if proper:
return ((obj.low < criteria.low and criteria.high <= obj.high) or (
obj.low <= criteria.low and criteria.high < obj.high))
else:
return obj.low <= criteria.low and criteria.high <= obj.high
elif superset:
if proper:
return ((criteria.low < obj.low and obj.high <= criteria.high) or (
criteria.low <= obj.low and obj.high < criteria.high))
else:
return (criteria.low <= obj.low and obj.high <= criteria.high)
else:
return criteria.low == obj.low and obj.high == criteria.high
def match_level(obj: Level, criteria: Level, dom: bool, domby: bool, incomp: bool) -> bool:
"""
Match the an MLS level.
obj The level to match.
criteria The criteria to match. (a level)
dom If true, the criteria will match if it dominates obj.
domby If true, the criteria will match if it is dominated by obj.
incomp If true, the criteria will match if it is incomparable to obj.
"""
if dom:
return (criteria >= obj)
elif domby:
return (criteria <= obj)
elif incomp:
return (criteria ^ obj)
else:
return (criteria == obj)
def validate_perms_any(perms: Iterable[str], tclass: Optional[Iterable[ObjClass]] = None,
policy: Optional[SELinuxPolicy] = None) -> None:
"""
Validate that each permission is valid for at least one
of specified object classes. If no classes are specified,
then all classes in the policy are checked.
A tclass or policy must be specified.
Parameters:
perms A container of str permission names.
Keyword Parameters.
tclass An iterable of 1 or more ObjClass.
policy A SELinuxPolicy
Exceptions:
ValueError Invalid parameter.
InvalidPermission One or more permissions is invalid.
Return: None
"""
if not perms:
raise ValueError("No permissions specified.")
if tclass:
# make local mutable set
selected_classes = set(c for c in tclass)
elif policy:
selected_classes = set(policy.classes())
else:
raise ValueError("No object class(es) or policy specified.")
invalid = set(p for p in perms)
for c in selected_classes:
invalid -= c.perms
with suppress(NoCommon):
invalid -= c.common.perms
if not invalid:
break
else:
if tclass:
raise InvalidPermission(
"Permission(s) do not exist in the specified classes: {}"
.format(", ".join(invalid)))
else:
raise InvalidPermission(
"Permission(s) do not exist any class: {}"
.format(", ".join(invalid)))
def xperm_str_to_tuple_ranges(perms: str, separator: str = ",") -> List[Tuple[int, int]]:
"""
Create a extended permission list of ranges from a string representation of ranges.
This does not do any checking for out-of-range values.
Parameters:
perms A string representation of integer extended permissions, such as
"0x08,0x30-0x40,0x55,0x60-0x65"
Keyword Parameters:
separator The separator between permissions/permission ranges.
Default is ","
Return: List[Tuple[int, int]] equivalent of the permissions.
"""
xperms: List[Tuple[int, int]] = []
for item in perms.split(separator):
rng = item.split("-")
if len(rng) == 2:
xperms.append((int(rng[0], base=16), int(rng[1], base=16)))
elif len(rng) == 1:
xperms.append((int(rng[0], base=16), int(rng[0], base=16)))
else:
raise ValueError("Unable to parse \"{}\" for xperms.".format(item))
return xperms
