#! /usr/bin/python -E
# Authors: Simo Sorce <ssorce@redhat.com>
#
# Copyright (C) 2007 Simo Sorce <ssorce@redhat.com>
# see file 'COPYING' for use and warranty information
#
# 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; version 2 or later
#
# 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, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#

etckrb5conf = "/etc/krb5.conf"
krb5dir = "/var/kerberos/krb5kdc"
cachedir = "/var/cache/ipa"
libdir = "/var/lib/ipa"
basedir = libdir+"/mkey"
ourkrb5conf = basedir+"/krb5.conf"
ldappwdfile = basedir+"/ldappwd"

password = ""

import sys
try:
    from optparse import OptionParser
    import ipa
    import ipa.config
    import ipa.ipautil
    from ipaclient import ipachangeconf
    from ipaserver import ipaldap

    import krbV

    import ldap
    from ldap import LDAPError
    from ldap import ldapobject

    from pyasn1.type import univ, namedtype
    import pyasn1.codec.ber.encoder
    import pyasn1.codec.ber.decoder
    import struct
    import base64

    import random
    import time
    import os
    import shutil
    import getpass
except ImportError:
    print >> sys.stderr, """\
There was a problem importing one of the required Python modules. The
error was:

    %s
""" % sys.exc_value
    sys.exit(1)

def parse_options():
    parser = OptionParser("%prog [-q|--quiet] [-p DM_PASSWORD]")
    parser.add_option("-p", "--dm-password", dest="dm_password",
                      help="The Directory Manager password")
    parser.add_option("-q", "--quiet", action="store_true", dest="quiet",
                      help="Keep quiet")

    ipa.config.add_standard_options(parser)
    options, args = parser.parse_args()

    ipa.config.verify_args(parser, args)
    ipa.config.init_config(options)

    return options, args

# We support only des3 encoded stash files for now
def generate_new_stash_file(file):

    odd_parity_bytes_pool = ['\x01', '\x02', '\x04', '\x07', '\x08', '\x0b',
        '\r', '\x0e', '\x10', '\x13', '\x15', '\x16', '\x19', '\x1a', '\x1c',
        '\x1f', ' ', '#', '%', '&', ')', '*', ',', '/', '1', '2', '4', '7', '8',
        ';', '=', '>', '@', 'C', 'E', 'F', 'I', 'J', 'L', 'O', 'Q', 'R', 'T',
        'W', 'X', '[', ']', '^', 'a', 'b', 'd', 'g', 'h', 'k', 'm', 'n', 'p',
        's', 'u', 'v', 'y', 'z', '|', '\x7f', '\x80', '\x83', '\x85', '\x86',
        '\x89', '\x8a', '\x8c', '\x8f', '\x91', '\x92', '\x94', '\x97', '\x98',
        '\x9b', '\x9d', '\x9e', '\xa1', '\xa2', '\xa4', '\xa7', '\xa8', '\xab',
        '\xad', '\xae', '\xb0', '\xb3', '\xb5', '\xb6', '\xb9', '\xba', '\xbc',
        '\xbf', '\xc1', '\xc2', '\xc4', '\xc7', '\xc8', '\xcb', '\xcd', '\xce',
        '\xd0', '\xd3', '\xd5', '\xd6', '\xd9', '\xda', '\xdc', '\xdf', '\xe0',
        '\xe3', '\xe5', '\xe6', '\xe9', '\xea', '\xec', '\xef', '\xf1', '\xf2',
        '\xf4', '\xf7', '\xf8', '\xfb', '\xfd', '\xfe']

    pool_len = len(odd_parity_bytes_pool)
    keytype = 16 # des3
    keydata = ""

    r = random.SystemRandom()
    for k in range(24):
        keydata += r.choice(odd_parity_bytes_pool)

    format = '=hi%ss' % len(keydata)
    s = struct.pack(format, keytype, len(keydata), keydata)
    try:
        fd = open(file, "w")
        fd.write(s)
    except os.error, e:
        logging.critical("failed to write stash file")
        raise e

# clean up procedures
def cleanup(password):
    try:
        os.stat(basedir)
    except:
        return None
    try:
        # always remove ldappwdfile as it contains the Directory Manager password
        os.remove(ldappwdfile)
    except:
        pass

    # tar and encrypt the working dir so that we do not leave sensitive data
    # around unproteceted
    curtime = time.strftime("%Y%m%d%H%M%S",time.gmtime())
    tarfile = libdir+"/ipa-change-mkey-"+curtime+".tar"
    gpgfile = tarfile+".gpg"
    args = ['/bin/tar', '-C', libdir, '-cf', tarfile, 'mkey']
    ipa.ipautil.run(args)
    ipa.ipautil.encrypt_file(tarfile, gpgfile, password, cachedir)
    os.remove(tarfile)
    shutil.rmtree(basedir, ignore_errors=True)

    return "The temporary working directory with backup dump files has been securely archived and gpg-encrypted as "+gpgfile+" using the Directory Manager password."

def main():

    global password

    options, args = parse_options()

    krbctx = krbV.default_context()

    realm = krbctx.default_realm
    suffix = ipa.ipautil.realm_to_suffix(realm)

    backupfile = basedir+"/backup.dump"
    convertfile = basedir+"/convert.dump"
    oldstashfile = krb5dir+"/.k5."+realm
    newstashfile = basedir+"/.new.mkey"
    bkpstashfile = basedir+"/.k5."+realm

    if os.getuid() != 0:
        print "ERROR: This command must be run as root"
        sys.exit(1)

    print "DANGER: This is a dangerous operation, make sure you backup all your IPA data before running the tool"
    print "This command will restart your Directory and KDC Servers."

    #TODO: ask for confirmation
    if not ipa.ipautil.user_input("Do you want to proceed and change the Kerberos Master key?", False):
        print ""
        print "Aborting..."
        return 1

    password = options.dm_password
    if not password:
        password = getpass.getpass("Directory Manager password: ")

    # get a connection to the DS
    try:
        conn = ipaldap.IPAdmin(ipa.config.config.default_server[0])
        conn.do_simple_bind(bindpw=password)
    except Exception, e:
        print "ERROR: Could not connect to the Directory Server on "+ipa.config.config.default_server[0]+" ("+str(e)+")"
        return 1

    #  Wipe basedir and recreate it
    shutil.rmtree(basedir, ignore_errors=True)
    os.mkdir(basedir, 0700)

    generate_new_stash_file(newstashfile)

    # Generate conf files
    try:
        shutil.copyfile(etckrb5conf, ourkrb5conf)

        krbconf = ipachangeconf.IPAChangeConf("IPA Installer")
        krbconf.setOptionAssignment(" = ")
        krbconf.setSectionNameDelimiters(("[","]"))
        krbconf.setSubSectionDelimiters(("{","}"))
        krbconf.setIndent(("","  ","    "))

        #OPTS
        opts = [{'name':'ldap_kadmind_dn', 'type':'option', 'action':'set', 'value':'cn=Directory Manager'},
                {'name':'ldap_service_password_file', 'type':'option', 'action':'set', 'value':ldappwdfile}]

        #REALM
        realmopts = [{'name':realm, 'type':'subsection', 'action':'set', 'value':opts}]

        #DBMODULES
        dbopts = [{'name':'dbmodules', 'type':'section', 'action':'set', 'value':realmopts}]

        krbconf.changeConf(ourkrb5conf, dbopts);

        hexpwd = ""
        for x in password:
            hexpwd += (hex(ord(x))[2:])
        pwd_fd = open(ldappwdfile, "w")
        pwd_fd.write("cn=Directory Manager#{HEX}"+hexpwd+"\n")
        pwd_fd.close()
        os.chmod(ldappwdfile, 0600)

    except Exception, e:
        print "Failed to create custom configuration files ("+str(e)+") aborting..."
        return 1

    #Set environment vars so that the modified krb5.conf is used
    os.environ['KRB5_CONFIG'] = ourkrb5conf

    #Backup the kerberos key material for recovery if needed
    args = ["/usr/kerberos/sbin/kdb5_util", "dump", "-verbose", backupfile]
    print "Performing safety backup of the key material"
    try:
        output = ipa.ipautil.run(args)
    except ipa.ipautil.CalledProcessError, e:
        print "Failed to backup key material ("+str(e)+"), aborting ..."
        return 1

    if not options.quiet:
        princlist = output[1].split('\n')
        print "Principals stored into the backup file "+backupfile+":"
        for p in princlist:
            print p
        print ""

    #Convert the kerberos keys to the new master key
    args = ["/usr/kerberos/sbin/kdb5_util", "dump", "-verbose", "-new_mkey_file", newstashfile, convertfile]
    print "Converting key material to new master key"
    try:
        output = ipa.ipautil.run(args)
    except ipa.ipautil.CalledProcessError, e:
        print "Failed to convert key material, aborting ..."
        return 1

    savedprinclist = output[1].split('\n')

    if not options.quiet:
        princlist = output[1].split('\n')
        print "Principals dumped for conversion:"
        for p in princlist:
            print p
        print ""

    #Stop the KDC
    args = ["/etc/init.d/krb5kdc", "stop"]
    try:
        output = ipa.ipautil.run(args)
        if output[0]:
            print output[0]
        if output[1]:
            print output[1]
    except ipa.ipautil.CalledProcessError, e:
        print "WARNING: Failed to restart the KDC ("+str(e)+")"
        print "You will have to manually restart the KDC when the operation is completed"

    #Change the mkey into ldap
    try:
        stash = open(newstashfile, "r")
        keytype = struct.unpack('h', stash.read(2))[0]
        keylen = struct.unpack('i', stash.read(4))[0]
        keydata = stash.read(keylen)

        #encode it in the asn.1 attribute
        MasterKey = univ.Sequence()
        MasterKey.setComponentByPosition(0, univ.Integer(keytype))
        MasterKey.setComponentByPosition(1, univ.OctetString(keydata))
        krbMKey = univ.Sequence()
        krbMKey.setComponentByPosition(0, univ.Integer(0)) #we have no kvno
        krbMKey.setComponentByPosition(1, MasterKey)
        asn1key = pyasn1.codec.ber.encoder.encode(krbMKey)

        dn = "cn="+realm+",cn=kerberos,"+suffix
        mod = [(ldap.MOD_REPLACE, 'krbMKey', str(asn1key))]
        conn.modify_s(dn, mod)
    except Exception, e:
        print "ERROR: Failed to upload the Master Key from the Stash file: "+newstashfile+" ("+str(e)+")"
        return 1

    #Backup old stash file and substitute with new
    try:
        shutil.move(oldstashfile, bkpstashfile)
        shutil.copyfile(newstashfile, oldstashfile)
    except Exception, e:
        print "ERROR: An error occurred while installing the new stash file("+str(e)+")"
        print "The KDC may fail to start if the correct stash file is not in place"
        print "Verify that "+newstashfile+" has been correctly installed into "+oldstashfile
        print "A backup copy of the old stash file should be saved in "+bkpstashfile

    #Finally upload the converted principals
    args = ["/usr/kerberos/sbin/kdb5_util", "load", "-verbose", "-update", convertfile]
    print "Uploading converted key material"
    try:
        output = ipa.ipautil.run(args)
    except ipa.ipautil.CalledProcessError, e:
        print "Failed to upload key material ("+e+"), aborting ..."
        return 1

    if not options.quiet:
        princlist = output[1].split('\n')
        print "Principals converted and uploaded:"
        for p in princlist:
            print p
        print ""

    uploadedprinclist = output[1].split('\n')

    #Check for differences and report
    d = []
    for p in savedprinclist:
        if uploadedprinclist.count(p) == 0:
            d.append(p)
    if len(d) != 0:
        print "WARNING: Not all dumped principals have been updated"
        print "Principals not Updated:"
        for p in d:
            print p

    #Remove custom environ
    del os.environ['KRB5_CONFIG']

    #Restart Directory Server (the pwd plugin need to read the new mkey)
    args = ["/etc/init.d/dirsrv", "restart"]
    try:
        output = ipa.ipautil.run(args)
        if output[0]:
            print output[0]
        if output[1]:
            print output[1]
    except ipa.ipautil.CalledProcessError, e:
        print "WARNING: Failed to restart the Directory Server ("+str(e)+")"
        print "Please manually restart the DS with 'service dirsrv restart'"

    #Restart the KDC
    args = ["/etc/init.d/krb5kdc", "start"]
    try:
        output = ipa.ipautil.run(args)
        if output[0]:
            print output[0]
        if output[1]:
            print output[1]
    except ipa.ipautil.CalledProcessError, e:
        print "WARNING: Failed to restart the KDC ("+str(e)+")"
        print "Please manually restart the kdc with 'service krb5kdc start'"

    print "Master Password successfully changed"
    print "You MUST now copy the stash file "+oldstashfile+" to all the replicas and restart them!"
    print ""

    return 0

if __name__ == "__main__":
    ret = 0
    try:
        ret = main()
    except SystemExit, e:
        ret = e
    except KeyboardInterrupt, e:
        ret = 1
    except Exception, e:
        print "%s" % str(e)
        ret = 1

    try:
        msg = cleanup(password)
        if msg:
            print msg
    except Exception, e:
        print "Failed to clean up the temporary location for the dump files and generate and encrypted archive with error:"
        print e
        print "Please securely archive/encrypt "+basedir

    sys.exit(ret)