#!/usr/bin/env python3
# Copyright 2014-2015, Tresys Technology, LLC
#
# This file is part of SETools.
#
# SETools 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.
#
# SETools 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 SETools.  If not, see <http://www.gnu.org/licenses/>.
#

import sys
import argparse
import logging
import signal

import setools.dta


def print_transition(trans):
    if trans.transition:
        print("Domain transition rule(s):")
        for t in trans.transition:
            print(t)

        if trans.setexec:
            print("\nSet execution context rule(s):")
            for s in trans.setexec:
                print(s)

        for entrypoint in trans.entrypoints:
            print("\nEntrypoint {0}:".format(entrypoint.name))

            print("\tDomain entrypoint rule(s):")
            for e in entrypoint.entrypoint:
                print("\t{0}".format(e))

            print("\n\tFile execute rule(s):")
            for e in entrypoint.execute:
                print("\t{0}".format(e))

            if entrypoint.type_transition:
                print("\n\tType transition rule(s):")
                for t in entrypoint.type_transition:
                    print("\t{0}".format(t))

            print()

    if trans.dyntransition:
        print("Dynamic transition rule(s):")
        for d in trans.dyntransition:
            print(d)

        print("\nSet current process context rule(s):")
        for s in trans.setcurrent:
            print(s)

        print()

    print()


signal.signal(signal.SIGPIPE, signal.SIG_DFL)

parser = argparse.ArgumentParser(
    description="SELinux policy domain transition analysis tool.",
    epilog="If no analysis is selected, all forward transitions out of the source will be printed.")
parser.add_argument("--version", action="version", version=setools.__version__)
parser.add_argument("-p", "--policy", help="Path to SELinux policy to analyze.")
parser.add_argument("-s", "--source", help="Source type of the analysis.", required=True)
parser.add_argument("-t", "--target", help="Target type of the analysis.")
parser.add_argument("--stats", action="store_true",
                    help="Display statistics at the end of the analysis.")
parser.add_argument("-v", "--verbose", action="store_true",
                    help="Print extra informational messages")
parser.add_argument("--debug", action="store_true", dest="debug", help="Enable debugging.")

alg = parser.add_argument_group("Analysis algorithm")
alg.add_argument("-S", "--shortest_path", action="store_true",
                 help="Calculate all shortest paths.")
alg.add_argument("-A", "--all_paths", type=int, metavar="MAX_STEPS",
                 help="Calculate all paths, with the specified maximum path length. (Expensive)")

opts = parser.add_argument_group("Analysis options")
opts.add_argument("-r", "--reverse", action="store_true", default=False,
                  help="Perform a reverse DTA.")
opts.add_argument("-l", "--limit_trans", default=0, type=int,
                  help="Limit to the specified number of transitions.  Default is unlimited.")
opts.add_argument("exclude", help="List of excluded types in the analysis.", nargs="*")

args = parser.parse_args()

if not args.target and (args.shortest_path or args.all_paths):
    parser.error("The target type must be specified to determine a path.")

if args.target and not (args.shortest_path or args.all_paths):
    parser.error("An algorithm must be specified to determine a path.")

if args.debug:
    logging.basicConfig(level=logging.DEBUG,
                        format='%(asctime)s|%(levelname)s|%(name)s|%(message)s')
elif args.verbose:
    logging.basicConfig(level=logging.INFO, format='%(message)s')
else:
    logging.basicConfig(level=logging.WARNING, format='%(message)s')

try:
    p = setools.SELinuxPolicy(args.policy)
    g = setools.dta.DomainTransitionAnalysis(p, reverse=args.reverse, exclude=args.exclude)

    if args.shortest_path or args.all_paths:
        if args.shortest_path:
            paths = g.all_shortest_paths(args.source, args.target)
        else:
            paths = g.all_paths(args.source, args.target, args.all_paths)

        i = 0
        for i, path in enumerate(paths, start=1):
            print("Domain transition path {0}:".format(i))

            for stepnum, step in enumerate(path, start=1):

                print("Step {0}: {1} -> {2}\n".format(stepnum, step.source, step.target))
                print_transition(step)

            if args.limit_trans and i >= args.limit_trans:
                break

        print(i, "domain transition path(s) found.")

    else:  # single transition
        transitions = g.transitions(args.source)

        i = 0
        for i, step in enumerate(transitions, start=1):
            print("Transition {0}: {1} -> {2}\n".format(i, step.source, step.target))
            print_transition(step)

            if args.limit_trans and i >= args.limit_trans:
                break

        print(i, "domain transition(s) found.")

    if args.stats:
        print("\nGraph statistics:")
        print(g.get_stats())

except Exception as err:
    if args.debug:
        raise
    else:
        print(err)

    sys.exit(1)
