Mini Shell

# -*- coding: utf-8 -*-
#
# Copyright (C) 2011-2016 Red Hat, Inc.
#
# Authors:
# Thomas Woerner <twoerner@redhat.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

__all__ = [ "command_of_pid", "pid_of_sender", "uid_of_sender", "user_of_uid",
            "context_of_sender", "command_of_sender", "user_of_sender",
            "dbus_to_python", "dbus_signature",
            "dbus_introspection_prepare_properties",
            "dbus_introspection_add_properties" ]

import dbus
import pwd
import sys
from xml.dom import minidom

from firewall.core.logger import log

PY2 = sys.version < '3'

def command_of_pid(pid):
    """ Get command for pid from /proc """
    try:
        with open("/proc/%d/cmdline" % pid, "r") as f:
            cmd = f.readlines()[0].replace('\0', " ").strip()
    except Exception:
        return None
    return cmd

def pid_of_sender(bus, sender):
    """ Get pid from sender string using 
    org.freedesktop.DBus.GetConnectionUnixProcessID """

    dbus_obj = bus.get_object('org.freedesktop.DBus', '/org/freedesktop/DBus')
    dbus_iface = dbus.Interface(dbus_obj, 'org.freedesktop.DBus')

    try:
        pid = int(dbus_iface.GetConnectionUnixProcessID(sender))
    except ValueError:
        return None
    return pid

def uid_of_sender(bus, sender):
    """ Get user id from sender string using 
    org.freedesktop.DBus.GetConnectionUnixUser """

    dbus_obj = bus.get_object('org.freedesktop.DBus', '/org/freedesktop/DBus')
    dbus_iface = dbus.Interface(dbus_obj, 'org.freedesktop.DBus')

    try:
        uid = int(dbus_iface.GetConnectionUnixUser(sender))
    except ValueError:
        return None
    return uid

def user_of_uid(uid):
    """ Get user for uid from pwd """

    try:
        pws = pwd.getpwuid(uid)
    except Exception:
        return None
    return pws[0]

def context_of_sender(bus, sender):
    """ Get SELinux context from sender string using 
    org.freedesktop.DBus.GetConnectionSELinuxSecurityContext """

    dbus_obj = bus.get_object('org.freedesktop.DBus', '/org/freedesktop/DBus')
    dbus_iface = dbus.Interface(dbus_obj, 'org.freedesktop.DBus')

    try:
        context =  dbus_iface.GetConnectionSELinuxSecurityContext(sender)
    except Exception:
        return None

    return "".join(map(chr, dbus_to_python(context)))

def command_of_sender(bus, sender):
    """ Return command of D-Bus sender """

    return command_of_pid(pid_of_sender(bus, sender))

def user_of_sender(bus, sender):
    return user_of_uid(uid_of_sender(bus, sender))

def dbus_to_python(obj, expected_type=None):
    if obj is None:
        python_obj = obj
    elif isinstance(obj, dbus.Boolean):
        python_obj = bool(obj)
    elif isinstance(obj, dbus.String):
        python_obj = obj.encode('utf-8') if PY2 else str(obj)
    elif PY2 and isinstance(obj, dbus.UTF8String):  # Python3 has no UTF8String
        python_obj = str(obj)
    elif isinstance(obj, dbus.ObjectPath):
        python_obj = str(obj)
    elif isinstance(obj, dbus.Byte) or \
            isinstance(obj, dbus.Int16) or \
            isinstance(obj, dbus.Int32) or \
            isinstance(obj, dbus.Int64) or \
            isinstance(obj, dbus.UInt16) or \
            isinstance(obj, dbus.UInt32) or \
            isinstance(obj, dbus.UInt64):
        python_obj = int(obj)
    elif isinstance(obj, dbus.Double):
        python_obj = float(obj)
    elif isinstance(obj, dbus.Array):
        python_obj = [dbus_to_python(x) for x in obj]
    elif isinstance(obj, dbus.Struct):
        python_obj = tuple([dbus_to_python(x) for x in obj])
    elif isinstance(obj, dbus.Dictionary):
        python_obj = {dbus_to_python(k): dbus_to_python(v) for k, v in obj.items()}
    elif isinstance(obj, bool) or \
         isinstance(obj, str) or isinstance(obj, bytes) or \
         isinstance(obj, int) or isinstance(obj, float) or \
         isinstance(obj, list) or isinstance(obj, tuple) or \
         isinstance(obj, dict):
        python_obj = obj
    else:
        raise TypeError("Unhandled %s" % repr(obj))

    if expected_type is not None:
        if (expected_type == bool and not isinstance(python_obj, bool)) or \
           (expected_type == str and not isinstance(python_obj, str)) or \
           (expected_type == int and not isinstance(python_obj, int)) or \
           (expected_type == float and not isinstance(python_obj, float)) or \
           (expected_type == list and not isinstance(python_obj, list)) or \
           (expected_type == tuple and not isinstance(python_obj, tuple)) or \
           (expected_type == dict and not isinstance(python_obj, dict)):
            raise TypeError("%s is %s, expected %s" % (python_obj, type(python_obj), expected_type))

    return python_obj

def dbus_signature(obj):
    if isinstance(obj, dbus.Boolean):
        return 'b'
    elif isinstance(obj, dbus.String):
        return 's'
    elif isinstance(obj, dbus.ObjectPath):
        return 'o'
    elif isinstance(obj, dbus.Byte):
        return 'y'
    elif isinstance(obj, dbus.Int16):
        return 'n'
    elif isinstance(obj, dbus.Int32):
        return 'i'
    elif isinstance(obj, dbus.Int64):
        return 'x'
    elif isinstance(obj, dbus.UInt16):
        return 'q'
    elif isinstance(obj, dbus.UInt32):
        return 'u'
    elif isinstance(obj, dbus.UInt64):
        return 't'
    elif isinstance(obj, dbus.Double):
        return 'd'
    elif isinstance(obj, dbus.Array):
        if len(obj.signature) > 1:
            return 'a(%s)' % obj.signature
        else:
            return 'a%s' % obj.signature
    elif isinstance(obj, dbus.Struct):
        return '(%s)' % obj.signature
    elif isinstance(obj, dbus.Dictionary):
        return 'a{%s}' % obj.signature
    elif PY2 and isinstance(obj, dbus.UTF8String):
        return 's'
    else:
        raise TypeError("Unhandled %s" % repr(obj))

def dbus_introspection_prepare_properties(obj, interface, access=None):
    if access is None:
        access = { }

    if not hasattr(obj, "_fw_dbus_properties"):
        setattr(obj, "_fw_dbus_properties", { })
    dip = getattr(obj, "_fw_dbus_properties")
    dip[interface] = { }

    try:
        _dict = obj.GetAll(interface)
    except Exception:
        _dict = { }
    for key,value in _dict.items():
        dip[interface][key] = { "type": dbus_signature(value) }
        if key in access:
            dip[interface][key]["access"] = access[key]
        else:
            dip[interface][key]["access"] = "read"

def dbus_introspection_add_properties(obj, data, interface):
    doc = minidom.parseString(data)

    if hasattr(obj, "_fw_dbus_properties"):
        for node in doc.getElementsByTagName("interface"):
            if node.hasAttribute("name") and \
               node.getAttribute("name") == interface:
                dip = { }
                if getattr(obj, "_fw_dbus_properties"):
                    dip = getattr(obj, "_fw_dbus_properties")
                if interface in dip:
                    for key,value in dip[interface].items():
                        prop = doc.createElement("property")
                        prop.setAttribute("name", key)
                        prop.setAttribute("type", value["type"])
                        prop.setAttribute("access", value["access"])
                        node.appendChild(prop)

    log.debug10(doc.toxml())
    new_data = doc.toxml()
    doc.unlink()
    return new_data