python/samba/sd_utils.py

   1 # Utility methods for security descriptor manipulation
   2 #
   3 # Copyright Nadezhda Ivanova 2010 <nivanova@samba.org>
   4 #
   5 # This program is free software; you can redistribute it and/or modify
   6 # it under the terms of the GNU General Public License as published by
   7 # the Free Software Foundation; either version 3 of the License, or
   8 # (at your option) any later version.
   9 #
  10 # This program 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 General Public License for more details.
  14 #
  15 # You should have received a copy of the GNU General Public License
  16 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17 #
  18
  19 """Utility methods for security descriptor manipulation."""
  20
  21 import samba
  22 from ldb import Message, MessageElement, Dn
  23 from ldb import FLAG_MOD_REPLACE, SCOPE_BASE
  24 from samba.ndr import ndr_pack, ndr_unpack
  25 from samba.dcerpc import security
  26
  27
  28 class SDUtils(object):
  29     """Some utilities for manipulation of security descriptors on objects."""
  30
  31     def __init__(self, samdb):
  32         self.ldb = samdb
  33         self.domain_sid = security.dom_sid(self.ldb.get_domain_sid())
  34
  35     def modify_sd_on_dn(self, object_dn, sd, controls=None):
  36         """Modify security descriptor using either SDDL string
  37             or security.descriptor object
  38         """
  39         m = Message()
  40         m.dn = Dn(self.ldb, object_dn)
  41         assert(isinstance(sd, str) or isinstance(sd, security.descriptor))
  42         if isinstance(sd, str):
  43             tmp_desc = security.descriptor.from_sddl(sd, self.domain_sid)
  44         elif isinstance(sd, security.descriptor):
  45             tmp_desc = sd
  46
  47         m["nTSecurityDescriptor"] = MessageElement(ndr_pack(tmp_desc),
  48                                                        FLAG_MOD_REPLACE,
  49                                                        "nTSecurityDescriptor")
  50         self.ldb.modify(m, controls)
  51
  52     def read_sd_on_dn(self, object_dn, controls=None):
  53         res = self.ldb.search(object_dn, SCOPE_BASE, None,
  54                               ["nTSecurityDescriptor"], controls=controls)
  55         desc = res[0]["nTSecurityDescriptor"][0]
  56         return ndr_unpack(security.descriptor, desc)
  57
  58     def get_object_sid(self, object_dn):
  59         res = self.ldb.search(object_dn)
  60         return ndr_unpack(security.dom_sid, res[0]["objectSid"][0])
  61
  62     def dacl_add_ace(self, object_dn, ace):
  63         """Add an ACE to an objects security descriptor
  64         """
  65         desc = self.read_sd_on_dn(object_dn)
  66         desc_sddl = desc.as_sddl(self.domain_sid)
  67         if ace in desc_sddl:
  68             return
  69         if desc_sddl.find("(") >= 0:
  70             desc_sddl = (desc_sddl[:desc_sddl.index("(")] + ace +
  71                          desc_sddl[desc_sddl.index("("):])
  72         else:
  73             desc_sddl = desc_sddl + ace
  74         self.modify_sd_on_dn(object_dn, desc_sddl)
  75
  76     def get_sd_as_sddl(self, object_dn, controls=None):
  77         """Return object nTSecutiryDescriptor in SDDL format
  78         """
  79         desc = self.read_sd_on_dn(object_dn, controls=controls)
  80         return desc.as_sddl(self.domain_sid)