path: root/daemons/dnssec/ipa-ods-exporter

#!/usr/bin/python2
#
# Copyright (C) 2014  FreeIPA Contributors see COPYING for license
#
"""
This is FreeIPA's replacement for signerd from OpenDNSSEC suite version 1.4.x.

This program uses the same socket and protocol as original signerd and should
be activated via systemd socket activation using "ods-signer" command line
utility.

Alternativelly, it can be called directly and a command can be supplied as
first command line argument.

Purpose of this replacement is to upload keys generated by OpenDNSSEC to LDAP.
"""

from binascii import hexlify
from datetime import datetime
import dateutil.tz
import dns.dnssec
import fcntl
from krbV import Krb5Error
import logging
import os
import subprocess
import socket
import sys
import systemd.daemon
import systemd.journal
import sqlite3
import time

import ipalib
from ipapython.dn import DN
from ipapython.ipa_log_manager import root_logger, standard_logging_setup
from ipapython import ipaldap
from ipapython import ipautil
from ipaserver.plugins.ldap2 import ldap2
from ipaplatform.paths import paths

from ipapython.dnssec.abshsm import sync_pkcs11_metadata, wrappingmech_name2id
from ipapython.dnssec.ldapkeydb import LdapKeyDB
from ipapython.dnssec.localhsm import LocalHSM
import _ipap11helper

DAEMONNAME = 'ipa-ods-exporter'
PRINCIPAL = None  # not initialized yet
WORKDIR = os.path.join(paths.VAR_OPENDNSSEC_DIR ,'tmp')
KEYTAB_FB = paths.IPA_ODS_EXPORTER_KEYTAB

ODS_SE_MAXLINE = 1024  # from ODS common/config.h
ODS_DB_LOCK_PATH = "%s%s" % (paths.OPENDNSSEC_KASP_DB, '.our_lock')

# TODO: MECH_RSA_OAEP
SECRETKEY_WRAPPING_MECH = 'rsaPkcs'
PRIVKEY_WRAPPING_MECH = 'aesKeyWrapPad'

# DNSKEY flag constants
dnskey_flag_by_value = {
    0x0001: 'SEP',
    0x0080: 'REVOKE',
    0x0100: 'ZONE'
}

def dnskey_flags_to_text_set(flags):
    """Convert a DNSKEY flags value to set texts
    @rtype: set([string])"""

    flags_set = set()
    mask = 0x1
    while mask <= 0x8000:
        if flags & mask:
            text = dnskey_flag_by_value.get(mask)
            if not text:
                text = hex(mask)
            flags_set.add(text)
        mask <<= 1
    return flags_set

def datetime2ldap(dt):
    return dt.strftime(ipalib.constants.LDAP_GENERALIZED_TIME_FORMAT)

def sql2datetime(sql_time):
    """Convert SQL date format from local time zone into UTC."""
    localtz = dateutil.tz.tzlocal()
    localtime = datetime.strptime(sql_time, "%Y-%m-%d %H:%M:%S").replace(
                                  tzinfo=localtz)
    utctz = dateutil.tz.gettz('UTC')
    return localtime.astimezone(utctz)

def sql2datetimes(row):
    row2key_map = {'generate': 'idnsSecKeyCreated',
                   'publish': 'idnsSecKeyPublish',
                   'active': 'idnsSecKeyActivate',
                   'retire': 'idnsSecKeyInactive',
                   'dead': 'idnsSecKeyDelete'}
    times = {}
    for column, key in row2key_map.iteritems():
        if row[column] is not None:
            times[key] = sql2datetime(row[column])
    return times

def sql2ldap_algorithm(sql_algorithm):
    return {"idnsSecAlgorithm": dns.dnssec.algorithm_to_text(sql_algorithm)}

def sql2ldap_flags(sql_flags):
    dns_flags = dnskey_flags_to_text_set(sql_flags)
    ldap_flags = {}
    for flag in dns_flags:
        attr = 'idnsSecKey%s' % flag
        ldap_flags[attr] = 'TRUE'
    return ldap_flags

def sql2ldap_keyid(sql_keyid):
    assert len(sql_keyid) % 2 == 0
    assert len(sql_keyid) > 0
    # TODO: this is huge hack. BIND has some problems with % notation in URIs.
    # Workaround: OpenDNSSEC uses same value for ID also for label (but in hex).
    uri = "pkcs11:object=%s" % sql_keyid
    #uri += '%'.join(sql_keyid[i:i+2] for i in range(0, len(sql_keyid), 2))
    return {"idnsSecKeyRef": uri}

class ods_db_lock(object):
    def __enter__(self):
        self.f = open(ODS_DB_LOCK_PATH, 'w')
        log.debug('waiting for lock %r', self.f)
        fcntl.lockf(self.f, fcntl.LOCK_EX)
        log.debug('acquired lock %r', self.f)

    def __exit__(self, *args):
        fcntl.lockf(self.f, fcntl.LOCK_UN)
        log.debug('released lock %r', self.f)
        self.f.close()

def get_ldap_zone(ldap, dns_base, name):
    zone_names = ["%s." % name, name]

    # find zone object: name can optionally end with period
    ldap_zone = None
    for zone_name in zone_names:
        zone_base = DN("idnsname=%s" % zone_name, dns_base)
        try:
            ldap_zone = ldap.get_entry(dn=zone_base,
                                       attrs_list=["idnsname"])
            break
        except ipalib.errors.NotFound:
            continue

    assert ldap_zone is not None, 'DNS zone "%s" should exist in LDAP' % name

    return ldap_zone

def get_ldap_keys_dn(zone_dn):
    """Container DN"""
    return DN("cn=keys", zone_dn)

def get_ldap_keys(ldap, zone_dn):
    """Keys objects"""
    keys_dn = get_ldap_keys_dn(zone_dn)
    ldap_filter = ldap.make_filter_from_attr('objectClass', 'idnsSecKey')
    ldap_keys = ldap.get_entries(base_dn=keys_dn, filter=ldap_filter)

    return ldap_keys

def get_ods_keys(zone_name):
    # get zone ID
    cur = db.execute("SELECT id FROM zones WHERE LOWER(name)=LOWER(?)",
                     (zone_name,))
    rows = cur.fetchall()
    assert len(rows) == 1, "exactly one DNS zone should exist in ODS DB"
    zone_id = rows[0][0]

    # get all keys for given zone ID
    cur = db.execute("SELECT kp.HSMkey_id, kp.generate, kp.algorithm, dnsk.publish, dnsk.active, dnsk.retire, dnsk.dead, dnsk.keytype "
             "FROM keypairs AS kp JOIN dnsseckeys AS dnsk ON kp.id = dnsk.id "
             "WHERE dnsk.zone_id = ?", (zone_id,))
    keys = {}
    for row in cur:
        key_data = sql2datetimes(row)
        if 'idnsSecKeyDelete' in key_data \
            and key_data['idnsSecKeyDelete'] > datetime.now():
                continue  # ignore deleted keys

        key_data.update(sql2ldap_flags(row['keytype']))
        assert key_data.get('idnsSecKeyZONE', None) == 'TRUE', \
                'unexpected key type 0x%x' % row['keytype']
        if key_data.get('idnsSecKeySEP', 'FALSE') == 'TRUE':
            key_type = 'KSK'
        else:
            key_type = 'ZSK'

        key_data.update(sql2ldap_algorithm(row['algorithm']))
        key_id = "%s-%s-%s" % (key_type,
                               datetime2ldap(key_data['idnsSecKeyCreated']),
                               row['HSMkey_id'])

        key_data.update(sql2ldap_keyid(row['HSMkey_id']))
        keys[key_id] = key_data
        log.debug("key %s metadata: %s", key_id, key_data)

    return keys

def sync_set_metadata_2ldap(log, source_set, target_set):
    """sync metadata from source key set to target key set in LDAP

    Keys not present in both sets are left intact."""
    log = log.getChild('sync_set_metadata_2ldap')
    matching_keys = set(source_set.keys()).intersection(set(target_set.keys()))
    log.info("keys in local HSM & LDAP: %s", hex_set(matching_keys))
    for key_id in matching_keys:
        sync_pkcs11_metadata(log, source_set[key_id], target_set[key_id])

def ldap2master_replica_keys_sync(log, ldapkeydb, localhsm):
    """LDAP=>master's local HSM replica key synchronization"""
    # import new replica keys from LDAP
    log = log.getChild('ldap2master_replica')
    log.debug("replica pub keys in LDAP: %s", hex_set(ldapkeydb.replica_pubkeys_wrap))
    log.debug("replica pub keys in SoftHSM: %s", hex_set(localhsm.replica_pubkeys_wrap))
    new_replica_keys = set(ldapkeydb.replica_pubkeys_wrap.keys()) \
            - set(localhsm.replica_pubkeys_wrap.keys())
    log.info("new replica keys in LDAP: %s", hex_set(new_replica_keys))
    for key_id in new_replica_keys:
        new_key_ldap = ldapkeydb.replica_pubkeys_wrap[key_id]
        log.error('label=%s,  id=%s, data=%s',
                new_key_ldap['ipk11label'],
                hexlify(new_key_ldap['ipk11id']),
                hexlify(new_key_ldap['ipapublickey']))
        localhsm.import_public_key(new_key_ldap, new_key_ldap['ipapublickey'])

    # set CKA_WRAP = FALSE for all replica keys removed from LDAP
    removed_replica_keys = set(localhsm.replica_pubkeys_wrap.keys()) \
            - set(ldapkeydb.replica_pubkeys_wrap.keys())
    log.info("obsolete replica keys in local HSM: %s",
            hex_set(removed_replica_keys))
    for key_id in removed_replica_keys:
        localhsm.replica_pubkeys_wrap[key_id]['ipk11wrap'] = False

    # synchronize replica key attributes from LDAP to local HSM
    sync_set_metadata_2ldap(log, localhsm.replica_pubkeys_wrap,
            ldapkeydb.replica_pubkeys_wrap)

def master2ldap_master_keys_sync(log, ldapkeydb, localhsm):
    ## master key -> LDAP synchronization
    # export new master keys to LDAP
    new_master_keys = set(localhsm.master_keys.keys()) \
            - set(ldapkeydb.master_keys.keys())
    log.debug("master keys in local HSM: %s", hex_set(localhsm.master_keys.keys()))
    log.debug("master keys in LDAP HSM: %s", hex_set(ldapkeydb.master_keys.keys()))
    log.debug("new master keys in local HSM: %s", hex_set(new_master_keys))
    for mkey_id in new_master_keys:
        mkey = localhsm.master_keys[mkey_id]
        ldapkeydb.import_master_key(mkey)

    # re-fill cache with keys we just added
    ldapkeydb.flush()
    log.debug('master keys in LDAP after flush: %s', hex_set(ldapkeydb.master_keys))

    # synchronize master key metadata to LDAP
    for mkey_id, mkey_local in localhsm.master_keys.iteritems():
        log.debug('synchronizing master key metadata: 0x%s', hexlify(mkey_id))
        sync_pkcs11_metadata(log, mkey_local, ldapkeydb.master_keys[mkey_id])

    # re-wrap all master keys in LDAP with new replica keys (as necessary)
    enabled_replica_key_ids = set(localhsm.replica_pubkeys_wrap.keys())
    log.debug('enabled replica key ids: %s', hex_set(enabled_replica_key_ids))

    for mkey_id, mkey_ldap in ldapkeydb.master_keys.iteritems():
        log.debug('processing master key data: 0x%s', hexlify(mkey_id))

        # check that all active replicas have own copy of master key
        used_replica_keys = set()
        for wrapped_entry in mkey_ldap.wrapped_entries:
            matching_keys = localhsm.find_keys(
                    uri=wrapped_entry.single_value['ipaWrappingKey'])
            for matching_key in matching_keys.itervalues():
                assert matching_key['ipk11label'].startswith(u'dnssec-replica:'), \
                        'Wrapped key "%s" refers to PKCS#11 URI "%s" which is ' \
                        'not a know DNSSEC replica key: label "%s" does not start ' \
                        'with "dnssec-replica:" prefix' % (wrapped_entry.dn,
                                wrapped_entry['ipaWrappingKey'],
                                matching_key['ipk11label'])
                used_replica_keys.add(matching_key['ipk11id'])

        new_replica_keys = enabled_replica_key_ids - used_replica_keys
        log.debug('master key 0x%s is not wrapped with replica keys %s',
                hexlify(mkey_id), hex_set(new_replica_keys))

        # wrap master key with new replica keys
        mkey_local = localhsm.find_keys(id=mkey_id).popitem()[1]
        for replica_key_id in new_replica_keys:
            log.info('adding master key 0x%s wrapped with replica key 0x%s' % (
                hexlify(mkey_id), hexlify(replica_key_id)))
            replica_key = localhsm.replica_pubkeys_wrap[replica_key_id]
            keydata = localhsm.p11.export_wrapped_key(mkey_local.handle,
                    replica_key.handle, _ipap11helper.MECH_RSA_PKCS)
            mkey_ldap.add_wrapped_data(keydata, SECRETKEY_WRAPPING_MECH,
                    replica_key_id)

    ldapkeydb.flush()

def master2ldap_zone_keys_sync(log, ldapkeydb, localhsm):
    # synchroniza zone keys
    log = log.getChild('master2ldap_zone_keys')
    keypairs_ldap = ldapkeydb.zone_keypairs
    log.debug("zone keys in LDAP: %s", hex_set(keypairs_ldap))

    pubkeys_local = localhsm.zone_pubkeys
    privkeys_local = localhsm.zone_privkeys
    log.debug("zone keys in local HSM: %s", hex_set(privkeys_local))

    assert set(pubkeys_local) == set(privkeys_local), \
            "IDs of private and public keys for DNS zones in local HSM does " \
            "not match to key pairs: %s vs. %s" % \
            (hex_set(pubkeys_local), hex_set(privkeys_local))

    new_keys = set(pubkeys_local) - set(keypairs_ldap)
    log.debug("new zone keys in local HSM: %s", hex_set(new_keys))
    mkey = localhsm.active_master_key
    # wrap each new zone key pair with selected master key
    for zkey_id in new_keys:
        pubkey = pubkeys_local[zkey_id]
        pubkey_data = localhsm.p11.export_public_key(pubkey.handle)

        privkey = privkeys_local[zkey_id]
        privkey_data = localhsm.p11.export_wrapped_key(privkey.handle,
                wrapping_key=mkey.handle,
                wrapping_mech=wrappingmech_name2id[PRIVKEY_WRAPPING_MECH])
        ldapkeydb.import_zone_key(pubkey, pubkey_data, privkey, privkey_data,
                PRIVKEY_WRAPPING_MECH, mkey['ipk11id'])

    sync_set_metadata_2ldap(log, pubkeys_local, keypairs_ldap)
    sync_set_metadata_2ldap(log, privkeys_local, keypairs_ldap)
    ldapkeydb.flush()


def hex_set(s):
    out = set()
    for i in s:
        out.add("0x%s" % hexlify(i))
    return out

def receive_systemd_command(log):
    fds = systemd.daemon.listen_fds()
    if len(fds) != 1:
        raise KeyError('Exactly one socket is expected.')

    sck = socket.fromfd(fds[0], socket.AF_UNIX, socket.SOCK_STREAM)

    conn, addr = sck.accept()
    log.debug('accepted new connection %s', repr(conn))

    # this implements cmdhandler_handle_cmd() logic
    cmd = conn.recv(ODS_SE_MAXLINE).strip()
    log.debug('received command "%s" from systemd socket', cmd)
    return (cmd, conn)

def parse_command(cmd):
    """Parse command to (exit code, message, zone_name) tuple.

    Exit code None means that execution should continue.
    """
    if cmd == 'ipa-hsm-update':
        return (0,
                'HSM synchronization finished, exiting.',
                None)

    elif cmd == 'ipa-full-update':
        return (None,
                'Synchronization of all zones requested.',
                None)

    elif not cmd.startswith('update '):
        return (0,
                'Command "%s" is not supported by IPA; '
                'HSM synchronization was finished and the command '
                'will be ignored.' % cmd,
                None)

    else:
        zone_name = cmd2ods_zone_name(cmd)
        return (None,
                'Update request for zone "%s" queued.\n' % zone_name,
                zone_name)

def send_systemd_reply(conn, reply):
        # Reply & close connection early.
        # This is necessary to let Enforcer to unlock the ODS DB.
        conn.send(reply + '\n')
        conn.shutdown(socket.SHUT_RDWR)
        conn.close()

def cmd2ods_zone_name(cmd):
    # ODS stores zone name without trailing period
    zone_name = cmd[7:].strip()
    if len(zone_name) > 1 and zone_name[-1] == '.':
        zone_name = zone_name[:-1]

    return zone_name

def sync_zone(log, ldap, dns_dn, zone_name):
    log.debug('synchronizing zone "%s"', zone_name)
    ods_keys = get_ods_keys(zone_name)
    ods_keys_id = set(ods_keys.keys())

    ldap_zone = get_ldap_zone(ldap, dns_dn, zone_name)
    zone_dn = ldap_zone.dn

    keys_dn = get_ldap_keys_dn(zone_dn)
    try:
        ldap_keys = get_ldap_keys(ldap, zone_dn)
    except ipalib.errors.NotFound:
        # cn=keys container does not exist, create it
        ldap_keys = []
        ldap_keys_container = ldap.make_entry(keys_dn,
                                              objectClass=['nsContainer'])
        try:
            ldap.add_entry(ldap_keys_container)
        except ipalib.errors.DuplicateEntry:
            # ldap.get_entries() does not distinguish non-existent base DN
            # from empty result set so addition can fail because container
            # itself exists already
            pass

    ldap_keys_dict = {}
    for ldap_key in ldap_keys:
        cn = ldap_key['cn'][0]
        ldap_keys_dict[cn] = ldap_key

    ldap_keys = ldap_keys_dict  # shorthand
    ldap_keys_id = set(ldap_keys.keys())

    new_keys_id = ods_keys_id - ldap_keys_id
    log.info('new keys from ODS: %s', new_keys_id)
    for key_id in new_keys_id:
        cn = "cn=%s" % key_id
        key_dn = DN(cn, keys_dn)
        log.debug('adding key "%s" to LDAP', key_dn)
        ldap_key = ldap.make_entry(key_dn,
                                   objectClass=['idnsSecKey'],
                                   **ods_keys[key_id])
        ldap.add_entry(ldap_key)

    deleted_keys_id = ldap_keys_id - ods_keys_id
    log.info('deleted keys in LDAP: %s', deleted_keys_id)
    for key_id in deleted_keys_id:
        cn = "cn=%s" % key_id
        key_dn = DN(cn, keys_dn)
        log.debug('deleting key "%s" from LDAP', key_dn)
        ldap.delete_entry(key_dn)

    update_keys_id = ldap_keys_id.intersection(ods_keys_id)
    log.info('keys in LDAP & ODS: %s', update_keys_id)
    for key_id in update_keys_id:
        ldap_key = ldap_keys[key_id]
        ods_key = ods_keys[key_id]
        log.debug('updating key "%s" in LDAP', ldap_key.dn)
        ldap_key.update(ods_key)
        try:
            ldap.update_entry(ldap_key)
        except ipalib.errors.EmptyModlist:
            continue


log = logging.getLogger('root')
# this service is usually socket-activated
log.addHandler(systemd.journal.JournalHandler())
log.setLevel(level=logging.DEBUG)

if len(sys.argv) > 2:
    print __doc__
    sys.exit(1)
# program was likely invoked from console, log to it
elif len(sys.argv) == 2:
    console = logging.StreamHandler()
    log.addHandler(console)

# IPA framework initialization
ipalib.api.bootstrap(in_server=True, log=None)  # no logging to file
ipalib.api.finalize()

# Kerberos initialization
PRINCIPAL = str('%s/%s' % (DAEMONNAME, ipalib.api.env.host))
log.debug('Kerberos principal: %s', PRINCIPAL)
ccache_name = os.path.join(WORKDIR, 'ipa-ods-exporter.ccache')

try:
    ipautil.kinit_keytab(PRINCIPAL, paths.IPA_ODS_EXPORTER_KEYTAB, ccache_name,
                         attempts=5)
except Krb5Error as e:
    log.critical('Kerberos authentication failed: %s', e)
    sys.exit(1)

os.environ['KRB5CCNAME'] = ccache_name
log.debug('Got TGT')

# LDAP initialization
dns_dn = DN(ipalib.api.env.container_dns, ipalib.api.env.basedn)
ldap = ipalib.api.Backend[ldap2]
# fixme
log.debug('Connecting to LDAP')
ldap.connect(ccache=ccache_name)
log.debug('Connected')


### DNSSEC master: key synchronization
ldapkeydb = LdapKeyDB(log, ldap, DN(('cn', 'keys'), ('cn', 'sec'),
                                    ipalib.api.env.container_dns,
                                    ipalib.api.env.basedn))
localhsm = LocalHSM(paths.LIBSOFTHSM2_SO, 0,
        open(paths.DNSSEC_SOFTHSM_PIN).read())

ldap2master_replica_keys_sync(log, ldapkeydb, localhsm)
master2ldap_master_keys_sync(log, ldapkeydb, localhsm)
master2ldap_zone_keys_sync(log, ldapkeydb, localhsm)


### DNSSEC master: DNSSEC key metadata upload
# command receive is delayed so the command will stay in socket queue until
# the problem with LDAP server or HSM is fixed
try:
    cmd, conn = receive_systemd_command(log)
    if len(sys.argv) != 1:
        log.critical('No additional parameters are accepted when '
                     'socket activation is used.')
        sys.exit(1)
# Handle cases where somebody ran the program without systemd.
except KeyError as e:
    if len(sys.argv) != 2:
        print(__doc__)
        print('ERROR: Exactly one parameter or socket activation is required.')
        sys.exit(1)
    conn = None
    cmd = sys.argv[1]

exitcode, msg, zone_name = parse_command(cmd)

if conn:
    send_systemd_reply(conn, msg)
if exitcode is not None:
    log.info(msg)
    sys.exit(exitcode)
else:
    log.debug(msg)

# Open DB directly and read key timestamps etc.
with ods_db_lock():
    db = sqlite3.connect(paths.OPENDNSSEC_KASP_DB,
            isolation_level="EXCLUSIVE")
    db.row_factory = sqlite3.Row
    db.execute('BEGIN')

    if zone_name is not None:
        # only one zone should be processed
        sync_zone(log, ldap, dns_dn, zone_name)
    else:
        # process all zones
        for zone_row in db.execute("SELECT name FROM zones"):
            sync_zone(log, ldap, dns_dn, zone_row['name'])

log.debug('Done')