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      1 # Copyright 2014-2015, Tresys Technology, LLC
      2 #
      3 # This file is part of SETools.
      4 #
      5 # SETools is free software: you can redistribute it and/or modify
      6 # it under the terms of the GNU Lesser General Public License as
      7 # published by the Free Software Foundation, either version 2.1 of
      8 # the License, or (at your option) any later version.
      9 #
     10 # SETools is distributed in the hope that it will be useful,
     11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
     12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     13 # GNU Lesser General Public License for more details.
     14 #
     15 # You should have received a copy of the GNU Lesser General Public
     16 # License along with SETools.  If not, see
     17 # <http://www.gnu.org/licenses/>.
     18 #
     19 from . import exception
     20 from . import symbol
     21 from . import qpol
     22 
     23 
     24 def common_factory(policy, name):
     25     """Factory function for creating common permission set objects."""
     26 
     27     if isinstance(name, Common):
     28         assert name.policy == policy
     29         return name
     30     elif isinstance(name, qpol.qpol_common_t):
     31         return Common(policy, name)
     32 
     33     try:
     34         return Common(policy, qpol.qpol_common_t(policy, str(name)))
     35     except ValueError:
     36         raise exception.InvalidCommon("{0} is not a valid common".format(name))
     37 
     38 
     39 def class_factory(policy, name):
     40     """Factory function for creating object class objects."""
     41 
     42     if isinstance(name, ObjClass):
     43         assert name.policy == policy
     44         return name
     45     elif isinstance(name, qpol.qpol_class_t):
     46         return ObjClass(policy, name)
     47 
     48     try:
     49         return ObjClass(policy, qpol.qpol_class_t(policy, str(name)))
     50     except ValueError:
     51         raise exception.InvalidClass("{0} is not a valid object class".format(name))
     52 
     53 
     54 class Common(symbol.PolicySymbol):
     55 
     56     """A common permission set."""
     57 
     58     def __contains__(self, other):
     59         return other in self.perms
     60 
     61     @property
     62     def perms(self):
     63         """The list of the common's permissions."""
     64         return set(self.qpol_symbol.perm_iter(self.policy))
     65 
     66     def statement(self):
     67         return "common {0}\n{{\n\t{1}\n}}".format(self, '\n\t'.join(self.perms))
     68 
     69 
     70 class ObjClass(Common):
     71 
     72     """An object class."""
     73 
     74     def __contains__(self, other):
     75         try:
     76             if other in self.common.perms:
     77                 return True
     78         except exception.NoCommon:
     79             pass
     80 
     81         return other in self.perms
     82 
     83     @property
     84     def common(self):
     85         """
     86         The common that the object class inherits.
     87 
     88         Exceptions:
     89         NoCommon    The object class does not inherit a common.
     90         """
     91 
     92         try:
     93             return common_factory(self.policy, self.qpol_symbol.common(self.policy))
     94         except ValueError:
     95             raise exception.NoCommon("{0} does not inherit a common.".format(self))
     96 
     97     def statement(self):
     98         stmt = "class {0}\n".format(self)
     99 
    100         try:
    101             stmt += "inherits {0}\n".format(self.common)
    102         except exception.NoCommon:
    103             pass
    104 
    105         # a class that inherits may not have additional permissions
    106         perms = self.perms
    107         if len(perms) > 0:
    108             stmt += "{{\n\t{0}\n}}".format('\n\t'.join(perms))
    109 
    110         return stmt
    111