Add ipa-custodia service

Add a customized Custodia daemon and enable it after installation.
Generates server keys and loads them in LDAP autonomously on install
or update.
Provides client code classes too.

Signed-off-by: Simo Sorce <simo@redhat.com>
Reviewed-By: Jan Cholasta <jcholast@redhat.com>

6 files changed, 549 insertions, 0 deletions

diff --git a/ipapython/secrets/__init__.py b/ipapython/secrets/__init__.py
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/ipapython/secrets/__init__.py
diff --git a/ipapython/secrets/client.py b/ipapython/secrets/client.py
new file mode 100644
index 000000000..81d066f84
--- /dev/null
+++ b/ipapython/secrets/client.py
@@ -0,0 +1,99 @@
+# Copyright (C) 2015  IPA Project Contributors, see COPYING for license
+
+from __future__ import print_function
+from custodia.message.kem import KEMClient, KEY_USAGE_SIG, KEY_USAGE_ENC
+from jwcrypto.common import json_decode
+from jwcrypto.jwk import JWK
+from ipapython.secrets.kem import IPAKEMKeys
+from ipapython.secrets.store import iSecStore
+from ipaplatform.paths import paths
+from base64 import b64encode
+import ldapurl
+import gssapi
+import os
+import requests
+
+
+class CustodiaClient(object):
+
+    def _client_keys(self):
+        return self.ikk.server_keys
+
+    def _server_keys(self, server, realm):
+        principal = 'host/%s@%s' % (server, realm)
+        sk = JWK(**json_decode(self.ikk.find_key(principal, KEY_USAGE_SIG)))
+        ek = JWK(**json_decode(self.ikk.find_key(principal, KEY_USAGE_ENC)))
+        return (sk, ek)
+
+    def _ldap_uri(self, realm):
+        dashrealm = '-'.join(realm.split('.'))
+        socketpath = paths.SLAPD_INSTANCE_SOCKET_TEMPLATE % (dashrealm,)
+        return 'ldapi://' + ldapurl.ldapUrlEscape(socketpath)
+
+    def _keystore(self, realm, ldap_uri, auth_type):
+        config = dict()
+        if ldap_uri is None:
+            config['ldap_uri'] = self._ldap_uri(realm)
+        else:
+            config['ldap_uri'] = ldap_uri
+        if auth_type is not None:
+            config['auth_type'] = auth_type
+
+        return iSecStore(config)
+
+    def __init__(self, client, server, realm, ldap_uri=None, auth_type=None):
+        self.client = client
+        self.creds = None
+
+        self.service_name = gssapi.Name('HTTP@%s' % (server,),
+                                        gssapi.NameType.hostbased_service)
+        self.server = server
+
+        keyfile = os.path.join(paths.IPA_CUSTODIA_CONF_DIR, 'server.keys')
+        self.ikk = IPAKEMKeys({'server_keys': keyfile})
+
+        self.kemcli = KEMClient(self._server_keys(server, realm),
+                                self._client_keys())
+
+        self.keystore = self._keystore(realm, ldap_uri, auth_type)
+
+        # FIXME: Remove warnings about missig subjAltName
+        requests.packages.urllib3.disable_warnings()
+
+    def init_creds(self):
+        name = gssapi.Name('host@%s' % (self.client,),
+                           gssapi.NameType.hostbased_service)
+        store = {'client_keytab': paths.KRB5_KEYTAB,
+                 'ccache': 'MEMORY:Custodia_%s' % b64encode(os.urandom(8))}
+        return gssapi.Credentials(name=name, store=store, usage='initiate')
+
+    def _auth_header(self):
+        if not self.creds or self.creds.lifetime < 300:
+            self.creds = self.init_creds()
+        ctx = gssapi.SecurityContext(name=self.service_name, creds=self.creds)
+        authtok = ctx.step()
+        return {'Authorization': 'Negotiate %s' % b64encode(authtok)}
+
+    def fetch_key(self, keyname):
+
+        # Prepare URL
+        url = 'https://%s/ipa/keys/%s' % (self.server, keyname)
+
+        # Prepare signed/encrypted request
+        encalg = ('RSA1_5', 'A256CBC-HS512')
+        request = self.kemcli.make_request(keyname, encalg=encalg)
+
+        # Prepare Authentication header
+        headers = self._auth_header()
+
+        # Perform request
+        r = requests.get(url, headers=headers,
+                         params={'type': 'kem', 'value': request})
+        r.raise_for_status()
+        reply = r.json()
+
+        if 'type' not in reply or reply['type'] != 'kem':
+            raise RuntimeError('Invlid JSON response type')
+
+        value = self.kemcli.parse_reply(keyname, reply['value'])
+        self.keystore.set('keys/%s' % keyname, value)
diff --git a/ipapython/secrets/common.py b/ipapython/secrets/common.py
new file mode 100644
index 000000000..2b906b649
--- /dev/null
+++ b/ipapython/secrets/common.py
@@ -0,0 +1,45 @@
+# Copyright (C) 2015  IPA Project Contributors, see COPYING for license
+from __future__ import print_function
+import ldap
+import ldap.sasl
+import ldap.filter
+
+
+class iSecLdap(object):
+
+    def __init__(self, uri, auth_type=None):
+        self.uri = uri
+        if auth_type is not None:
+            self.auth_type = auth_type
+        else:
+            if uri.startswith('ldapi'):
+                self.auth_type = 'EXTERNAL'
+            else:
+                self.auth_type = 'GSSAPI'
+        self._basedn = None
+
+    @property
+    def basedn(self):
+        if self._basedn is None:
+            conn = self.connect()
+            r = conn.search_s('', ldap.SCOPE_BASE)
+            self._basedn = r[0][1]['defaultnamingcontext'][0]
+        return self._basedn
+
+    def connect(self):
+        conn = ldap.initialize(self.uri)
+        if self.auth_type == 'EXTERNAL':
+            auth_tokens = ldap.sasl.external(None)
+        elif self.auth_type == 'GSSAPI':
+            auth_tokens = ldap.sasl.sasl({}, 'GSSAPI')
+        else:
+            raise ValueError(
+                'Invalid authentication type: %s' % self.auth_type)
+        conn.sasl_interactive_bind_s('', auth_tokens)
+        return conn
+
+    def build_filter(self, formatstr, args):
+        escaped_args = dict()
+        for key, value in args.iteritems():
+            escaped_args[key] = ldap.filter.escape_filter_chars(value)
+        return formatstr.format(**escaped_args)
diff --git a/ipapython/secrets/kem.py b/ipapython/secrets/kem.py
new file mode 100644
index 000000000..2a5f384a7
--- /dev/null
+++ b/ipapython/secrets/kem.py
@@ -0,0 +1,205 @@
+# Copyright (C) 2015  IPA Project Contributors, see COPYING for license
+
+from __future__ import print_function
+from ipaplatform.paths import paths
+import ConfigParser
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives.asymmetric import rsa, ec
+from custodia.message.kem import KEMKeysStore
+from custodia.message.kem import KEY_USAGE_SIG, KEY_USAGE_ENC, KEY_USAGE_MAP
+from jwcrypto.common import json_decode, json_encode
+from jwcrypto.common import base64url_encode
+from jwcrypto.jwk import JWK
+from ipapython.secrets.common import iSecLdap
+from binascii import unhexlify
+import ldap
+
+
+IPA_REL_BASE_DN = 'cn=custodia,cn=ipa,cn=etc'
+IPA_KEYS_QUERY = '(&(ipaKeyUsage={usage:s})(memberPrincipal={princ:s}))'
+RFC5280_USAGE_MAP = {KEY_USAGE_SIG: 'digitalSignature',
+                     KEY_USAGE_ENC: 'dataEncipherment'}
+
+
+class KEMLdap(iSecLdap):
+
+    @property
+    def keysbase(self):
+        return '%s,%s' % (IPA_REL_BASE_DN, self.basedn)
+
+    def _encode_int(self, i):
+        I = hex(i).rstrip("L").lstrip("0x")
+        return base64url_encode(unhexlify((len(I) % 2) * '0' + I))
+
+    def _parse_public_key(self, ipa_public_key):
+        public_key = serialization.load_der_public_key(ipa_public_key,
+                                                       default_backend())
+        num = public_key.public_numbers()
+        if isinstance(num, rsa.RSAPublicNumbers):
+            return {'kty': 'RSA',
+                    'e': self._encode_int(num.e),
+                    'n': self._encode_int(num.n)}
+        elif isinstance(num, ec.EllipticCurvePublicNumbers):
+            if num.curve.name == 'secp256r1':
+                curve = 'P-256'
+            elif num.curve.name == 'secp384r1':
+                curve = 'P-384'
+            elif num.curve.name == 'secp521r1':
+                curve = 'P-521'
+            else:
+                raise TypeError('Unsupported Elliptic Curve')
+            return {'kty': 'EC',
+                    'crv': curve,
+                    'x': self._encode_int(num.x),
+                    'y': self._encode_int(num.y)}
+        else:
+            raise TypeError('Unknown Public Key type')
+
+    def get_key(self, usage, principal):
+        conn = self.connect()
+        scope = ldap.SCOPE_SUBTREE
+
+        ldap_filter = self.build_filter(IPA_KEYS_QUERY,
+                                        {'usage': RFC5280_USAGE_MAP[usage],
+                                         'princ': principal})
+        r = conn.search_s(self.keysbase, scope, ldap_filter)
+        if len(r) != 1:
+            raise ValueError("Incorrect number of results (%d) searching for"
+                             "public key for %s" % (len(r), principal))
+        ipa_public_key = r[0][1]['ipaPublicKey'][0]
+        jwk = self._parse_public_key(ipa_public_key)
+        jwk['use'] = KEY_USAGE_MAP[usage]
+        return json_encode(jwk)
+
+    def _format_public_key(self, key):
+        if isinstance(key, str):
+            jwkey = json_decode(key)
+            if 'kty' not in jwkey:
+                raise ValueError('Invalid key, missing "kty" attribute')
+            if jwkey['kty'] == 'RSA':
+                pubnum = rsa.RSAPublicNumbers(jwkey['e'], jwkey['n'])
+                pubkey = pubnum.public_key(default_backend())
+            elif jwkey['kty'] == 'EC':
+                if jwkey['crv'] == 'P-256':
+                    curve = ec.SECP256R1
+                elif jwkey['crv'] == 'P-384':
+                    curve = ec.SECP384R1
+                elif jwkey['crv'] == 'P-521':
+                    curve = ec.SECP521R1
+                else:
+                    raise TypeError('Unsupported Elliptic Curve')
+                pubnum = ec.EllipticCurvePublicNumbers(
+                    jwkey['x'], jwkey['y'], curve)
+                pubkey = pubnum.public_key(default_backend())
+            else:
+                raise ValueError('Unknown key type: %s' % jwkey['kty'])
+        elif isinstance(key, rsa.RSAPublicKey):
+            pubkey = key
+        elif isinstance(key, ec.EllipticCurvePublicKey):
+            pubkey = key
+        else:
+            raise TypeError('Unknown key type: %s' % type(key))
+
+        return pubkey.public_bytes(
+            encoding=serialization.Encoding.DER,
+            format=serialization.PublicFormat.SubjectPublicKeyInfo)
+
+    def set_key(self, usage, host, principal, key):
+        public_key = self._format_public_key(key)
+        conn = self.connect()
+        name = '%s/%s' % (KEY_USAGE_MAP[usage], host)
+        dn = 'cn=%s,%s' % (name, self.keysbase)
+        try:
+            mods = [('objectClass', ['nsContainer',
+                                     'ipaKeyPolicy',
+                                     'ipaPublicKeyObject',
+                                     'groupOfPrincipals']),
+                    ('cn', name),
+                    ('ipaKeyUsage', RFC5280_USAGE_MAP[usage]),
+                    ('memberPrincipal', principal),
+                    ('ipaPublicKey', public_key)]
+            conn.add_s(dn, mods)
+        except Exception:  # pylint: disable=broad-except
+            # This may fail if the entry already exists
+            mods = [(ldap.MOD_REPLACE, 'memberPrincipal', principal),
+                    (ldap.MOD_REPLACE, 'ipaPublicKey', public_key)]
+            conn.modify_s(dn, mods)
+
+
+def newServerKeys(path, keyid):
+    skey = JWK(generate='RSA', use='sig', kid=keyid)
+    ekey = JWK(generate='RSA', use='enc', kid=keyid)
+    with open(path, 'w+') as f:
+        f.write('[%s,%s]' % (skey.export(), ekey.export()))
+    return [skey.get_op_key('verify'), ekey.get_op_key('encrypt')]
+
+
+class IPAKEMKeys(KEMKeysStore):
+    """A KEM Keys Store.
+
+    This is a store that holds public keys of registered
+    clients allowed to use KEM messages. It takes the form
+    of an authorizer merely for the purpose of attaching
+    itself to a 'request' so that later on the KEM Parser
+    can fetch the appropariate key to verify/decrypt an
+    incoming request and make the payload available.
+
+    The KEM Parser will actually perform additional
+    authorization checks in this case.
+
+    SimplePathAuthz is extended here as we want to attach the
+    store only to requests on paths we are configured to
+    manage.
+    """
+
+    def __init__(self, config=None, ipaconf=paths.IPA_DEFAULT_CONF):
+        super(IPAKEMKeys, self).__init__(config)
+        conf = ConfigParser.ConfigParser()
+        conf.read(ipaconf)
+        self.host = conf.get('global', 'host')
+        self.realm = conf.get('global', 'realm')
+        self.ldap_uri = config.get('ldap_uri', None)
+        if self.ldap_uri is None:
+            self.ldap_uri = conf.get('global', 'ldap_uri', None)
+        self._server_keys = None
+
+    def find_key(self, kid, usage):
+        if kid is None:
+            raise TypeError('Key ID is None, should be a SPN')
+        conn = KEMLdap(self.ldap_uri)
+        return conn.get_key(usage, kid)
+
+    def generate_server_keys(self):
+        principal = 'host/%s@%s' % (self.host, self.realm)
+        # Neutralize the key with read if any
+        self._server_keys = None
+        # Generate private key and store it
+        pubkeys = newServerKeys(self.config['server_keys'], principal)
+        # Store public key in LDAP
+        ldapconn = KEMLdap(self.ldap_uri)
+        ldapconn.set_key(KEY_USAGE_SIG, self.host, principal, pubkeys[0])
+        ldapconn.set_key(KEY_USAGE_ENC, self.host, principal, pubkeys[1])
+
+    @property
+    def server_keys(self):
+        if self._server_keys is None:
+            with open(self.config['server_keys']) as f:
+                jsonkeys = f.read()
+            dictkeys = json_decode(jsonkeys)
+            self._server_keys = (JWK(**dictkeys[KEY_USAGE_SIG]),
+                                 JWK(**dictkeys[KEY_USAGE_ENC]))
+        return self._server_keys
+
+
+# Manual testing
+if __name__ == '__main__':
+    IKK = IPAKEMKeys({'paths': '/',
+                      'server_keys': '/etc/ipa/custodia/server.keys'})
+    IKK.generate_server_keys()
+    print(('SIG', IKK.server_keys[0].export_public()))
+    print(('ENC', IKK.server_keys[1].export_public()))
+    print(IKK.find_key('host/%s@%s' % (IKK.host, IKK.realm),
+                       usage=KEY_USAGE_SIG))
+    print(IKK.find_key('host/%s@%s' % (IKK.host, IKK.realm),
+                       usage=KEY_USAGE_ENC))
diff --git a/ipapython/secrets/store.py b/ipapython/secrets/store.py
new file mode 100644
index 000000000..8f2d79826
--- /dev/null
+++ b/ipapython/secrets/store.py
@@ -0,0 +1,199 @@
+# Copyright (C) 2015  IPA Project Contributors, see COPYING for license
+
+from __future__ import print_function
+from base64 import b64encode, b64decode
+from custodia.store.interface import CSStore
+from jwcrypto.common import json_decode, json_encode
+from ipaplatform.paths import paths
+from ipapython import ipautil
+from ipapython.secrets.common import iSecLdap
+import ldap
+import os
+import shutil
+import sys
+import StringIO
+import tempfile
+
+
+class UnknownKeyName(Exception):
+    pass
+
+
+class DBMAPHandler(object):
+
+    def __init__(self, config, dbmap, nickname):
+        raise NotImplementedError
+
+    def export_key(self):
+        raise NotImplementedError
+
+    def import_key(self, value):
+        raise NotImplementedError
+
+
+def log_error(error):
+    print(error, file=sys.stderr)
+
+
+def PKI_TOMCAT_password_callback():
+    password = None
+    with open(paths.PKI_TOMCAT_PASSWORD_CONF) as f:
+        for line in f.readlines():
+            key, value = line.strip().split('=')
+            if key == 'internal':
+                password = value
+                break
+    return password
+
+
+def HTTPD_password_callback():
+    with open(paths.ALIAS_PWDFILE_TXT) as f:
+        password = f.read()
+    return password
+
+
+class NSSCertDB(DBMAPHandler):
+
+    def __init__(self, config, dbmap, nickname):
+        if 'type' not in dbmap or dbmap['type'] != 'NSSDB':
+            raise ValueError('Invalid type "%s",'
+                             ' expected "NSSDB"' % (dbmap['type'],))
+        if 'path' not in dbmap:
+            raise ValueError('Configuration does not provide NSSDB path')
+        if 'pwcallback' not in dbmap:
+            raise ValueError('Configuration does not provide Password Calback')
+        self.nssdb_path = dbmap['path']
+        self.nickname = nickname
+        self.nssdb_password = dbmap['pwcallback']()
+
+    def export_key(self):
+        tdir = tempfile.mkdtemp(dir=paths.TMP)
+        try:
+            nsspwfile = os.path.join(tdir, 'nsspwfile')
+            with open(nsspwfile, 'w+') as f:
+                f.write(self.nssdb_password)
+            pk12pwfile = os.path.join(tdir, 'pk12pwfile')
+            password = b64encode(os.urandom(16))
+            with open(pk12pwfile, 'w+') as f:
+                f.write(password)
+            pk12file = os.path.join(tdir, 'pk12file')
+            ipautil.run([paths.PK12UTIL,
+                         "-d", self.nssdb_path,
+                         "-o", pk12file,
+                         "-n", self.nickname,
+                         "-k", nsspwfile,
+                         "-w", pk12pwfile])
+            with open(pk12file, 'r') as f:
+                data = f.read()
+        finally:
+            shutil.rmtree(tdir)
+        return json_encode({'export password': password,
+                            'pkcs12 data': b64encode(data)})
+
+    def import_key(self, value):
+        v = json_decode(value)
+        tdir = tempfile.mkdtemp(dir=paths.TMP)
+        try:
+            nsspwfile = os.path.join(tdir, 'nsspwfile')
+            with open(nsspwfile, 'w+') as f:
+                f.write(self.nssdb_password)
+            pk12pwfile = os.path.join(tdir, 'pk12pwfile')
+            with open(pk12pwfile, 'w+') as f:
+                f.write(v['export password'])
+            pk12file = os.path.join(tdir, 'pk12file')
+            with open(pk12file, 'w+') as f:
+                f.write(b64decode(v['pkcs12 data']))
+            ipautil.run([paths.PK12UTIL,
+                         "-d", self.nssdb_path,
+                         "-i", pk12file,
+                         "-n", self.nickname,
+                         "-k", nsspwfile,
+                         "-w", pk12pwfile])
+        finally:
+            shutil.rmtree(tdir)
+
+
+# Exfiltrate the DM password Hash so it can be set in replica's and this
+# way let a replica be install without knowing the DM password and yet
+# still keep the DM password synchronized across replicas
+class DMLDAP(DBMAPHandler):
+
+    def __init__(self, config, dbmap, nickname):
+        if 'type' not in dbmap or dbmap['type'] != 'DMLDAP':
+            raise ValueError('Invalid type "%s",'
+                             ' expected "DMLDAP"' % (dbmap['type'],))
+        if nickname != 'DMHash':
+            raise UnknownKeyName("Unknown Key Named '%s'" % nickname)
+        self.ldap = iSecLdap(config['ldap_uri'],
+                             config.get('auth_type', None))
+
+    def export_key(self):
+        conn = self.ldap.connect()
+        r = conn.search_s('cn=config', ldap.SCOPE_BASE,
+                          attrlist=['nsslapd-rootpw'])
+        if len(r) != 1:
+            raise RuntimeError('DM Hash not found!')
+        return json_encode({'dmhash': r[0][1]['nsslapd-rootpw'][0]})
+
+    def import_key(self, value):
+        v = json_decode(value)
+        conn = self.ldap.connect()
+        mods = [(ldap.MOD_REPLACE, 'nsslapd-rootpw', str(v['dmhash']))]
+        conn.modify_s('cn=config', mods)
+
+
+NAME_DB_MAP = {
+    'ca': {
+        'type': 'NSSDB',
+        'path': paths.PKI_TOMCAT_ALIAS_DIR,
+        'handler': NSSCertDB,
+        'pwcallback': PKI_TOMCAT_password_callback,
+    },
+    'ra': {
+        'type': 'NSSDB',
+        'path': paths.HTTPD_ALIAS_DIR,
+        'handler': NSSCertDB,
+        'pwcallback': HTTPD_password_callback,
+    },
+    'dm': {
+        'type': 'DMLDAP',
+        'handler': DMLDAP,
+    }
+}
+
+
+class iSecStore(CSStore):
+
+    def __init__(self, config=None):
+        self.config = config
+
+    def _get_handler(self, key):
+        path = key.split('/', 3)
+        if len(path) != 3 or path[0] != 'keys':
+            raise ValueError('Invalid name')
+        if path[1] not in NAME_DB_MAP:
+            raise UnknownKeyName("Unknown DB named '%s'" % path[1])
+        dbmap = NAME_DB_MAP[path[1]]
+        return dbmap['handler'](self.config, dbmap, path[2])
+
+    def get(self, key):
+        try:
+            key_handler = self._get_handler(key)
+            value = key_handler.export_key()
+        except Exception as e:  # pylint: disable=broad-except
+            log_error('Error retrievieng key "%s": %s' % (key, str(e)))
+            value = None
+        return value
+
+    def set(self, key, value, replace=False):
+        try:
+            key_handler = self._get_handler(key)
+            key_handler.import_key(value)
+        except Exception as e:  # pylint: disable=broad-except
+            log_error('Error storing key "%s": %s' % (key, str(e)))
+
+    def list(self, keyfilter=None):
+        raise NotImplementedError
+
+    def cut(self, key):
+        raise NotImplementedError
diff --git a/ipapython/setup.py.in b/ipapython/setup.py.in
index 882142e4b..bdefe7c9a 100644..100755
--- a/ipapython/setup.py.in
+++ b/ipapython/setup.py.in
@@ -67,6 +67,7 @@ def setup_package():
             package_dir = {'ipapython': ''},
             packages = ["ipapython",
                         "ipapython.dnssec",
+                        "ipapython.secrets",
                         "ipapython.install"],
         )
     finally: