path: root/src/plugins/ikev2/test/test_ikev2.py

import os
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes, hmac
from cryptography.hazmat.primitives.asymmetric import dh
from cryptography.hazmat.primitives.ciphers import (
    Cipher,
    algorithms,
    modes,
)
from scapy.layers.inet import IP, UDP, Ether
from scapy.packet import raw, Raw
from scapy.utils import long_converter
from framework import VppTestCase, VppTestRunner
from vpp_ikev2 import Profile, IDType


KEY_PAD = b"Key Pad for IKEv2"


# defined in rfc3526
# tuple structure is (p, g, key_len)
DH = {
    '2048MODPgr': (long_converter("""
    FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1
    29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD
    EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245
    E485B576 625E7EC6 F44C42E9 A637ED6B 0BFF5CB6 F406B7ED
    EE386BFB 5A899FA5 AE9F2411 7C4B1FE6 49286651 ECE45B3D
    C2007CB8 A163BF05 98DA4836 1C55D39A 69163FA8 FD24CF5F
    83655D23 DCA3AD96 1C62F356 208552BB 9ED52907 7096966D
    670C354E 4ABC9804 F1746C08 CA18217C 32905E46 2E36CE3B
    E39E772C 180E8603 9B2783A2 EC07A28F B5C55DF0 6F4C52C9
    DE2BCBF6 95581718 3995497C EA956AE5 15D22618 98FA0510
    15728E5A 8AACAA68 FFFFFFFF FFFFFFFF"""), 2, 256)
}


class CryptoAlgo(object):
    def __init__(self, name, cipher, mode):
        self.name = name
        self.cipher = cipher
        self.mode = mode
        if self.cipher is not None:
            self.bs = self.cipher.block_size // 8

    def encrypt(self, data, key):
        iv = os.urandom(self.bs)
        encryptor = Cipher(self.cipher(key), self.mode(iv),
                           default_backend()).encryptor()
        return iv + encryptor.update(data) + encryptor.finalize()

    def decrypt(self, data, key, icv=None):
        iv = data[:self.bs]
        ct = data[self.bs:]
        decryptor = Cipher(algorithms.AES(key),
                           modes.CBC(iv),
                           default_backend()).decryptor()
        return decryptor.update(ct) + decryptor.finalize()

    def pad(self, data):
        pad_len = (len(data) // self.bs + 1) * self.bs - len(data)
        data = data + b'\x00' * (pad_len - 1)
        return data + bytes([pad_len])


class AuthAlgo(object):
    def __init__(self, name, mac, mod, key_len, trunc_len=None):
        self.name = name
        self.mac = mac
        self.mod = mod
        self.key_len = key_len
        self.trunc_len = trunc_len or key_len


CRYPTO_ALGOS = {
    'NULL': CryptoAlgo('NULL', cipher=None, mode=None),
    'AES-CBC': CryptoAlgo('AES-CBC', cipher=algorithms.AES, mode=modes.CBC),
}

AUTH_ALGOS = {
    'NULL': AuthAlgo('NULL', mac=None, mod=None, key_len=0, trunc_len=0),
    'HMAC-SHA1-96': AuthAlgo('HMAC-SHA1-96', hmac.HMAC, hashes.SHA1, 20, 12),
}

PRF_ALGOS = {
    'NULL': AuthAlgo('NULL', mac=None, mod=None, key_len=0, trunc_len=0),
    'PRF_HMAC_SHA2_256': AuthAlgo('PRF_HMAC_SHA2_256', hmac.HMAC,
                                  hashes.SHA256, 32),
}


class IKEv2ChildSA(object):
    def __init__(self, local_ts, remote_ts, spi=None):
        self.spi = spi or os.urandom(4)
        self.local_ts = local_ts
        self.remote_ts = remote_ts


class IKEv2SA(object):
    def __init__(self, test, is_initiator=True, spi=b'\x04' * 8,
                 id=None, id_type='fqdn', nonce=None, auth_data=None,
                 local_ts=None, remote_ts=None, auth_method='shared-key'):
        self.dh_params = None
        self.test = test
        self.is_initiator = is_initiator
        nonce = nonce or os.urandom(32)
        self.auth_data = auth_data
        if isinstance(id_type, str):
            self.id_type = IDType.value(id_type)
        else:
            self.id_type = id_type
        self.auth_method = auth_method
        if self.is_initiator:
            self.rspi = None
            self.ispi = spi
            self.i_id = id
            self.i_nonce = nonce
        else:
            self.rspi = spi
            self.ispi = None
            self.r_id = id
            self.r_nonce = None
        self.child_sas = [IKEv2ChildSA(local_ts, remote_ts)]

    def dh_pub_key(self):
        return self.i_dh_data

    def compute_secret(self):
        priv = self.dh_private_key
        peer = self.r_dh_data
        p, g, l = self.ike_group
        return pow(int.from_bytes(peer, 'big'),
                   int.from_bytes(priv, 'big'), p).to_bytes(l, 'big')

    def generate_dh_data(self):
        # generate DH keys
        if self.is_initiator:
            if self.ike_dh not in DH:
                raise NotImplementedError('%s not in DH group' % self.ike_dh)
            if self.dh_params is None:
                dhg = DH[self.ike_dh]
                pn = dh.DHParameterNumbers(dhg[0], dhg[1])
                self.dh_params = pn.parameters(default_backend())
            priv = self.dh_params.generate_private_key()
            pub = priv.public_key()
            x = priv.private_numbers().x
            self.dh_private_key = x.to_bytes(priv.key_size // 8, 'big')
            y = pub.public_numbers().y
            self.i_dh_data = y.to_bytes(pub.key_size // 8, 'big')

    def complete_dh_data(self):
        self.dh_shared_secret = self.compute_secret()

    def calc_child_keys(self):
        prf = self.ike_prf_alg.mod()
        s = self.i_nonce + self.r_nonce
        c = self.child_sas[0]

        encr_key_len = self.esp_crypto_key_len
        integ_key_len = self.ike_integ_alg.key_len
        l = (integ_key_len * 2 +
             encr_key_len * 2)
        keymat = self.calc_prfplus(prf, self.sk_d, s, l)

        pos = 0
        c.sk_ei = keymat[pos:pos+encr_key_len]
        pos += encr_key_len

        c.sk_ai = keymat[pos:pos+integ_key_len]
        pos += integ_key_len

        c.sk_er = keymat[pos:pos+encr_key_len]
        pos += encr_key_len

        c.sk_ar = keymat[pos:pos+integ_key_len]
        pos += integ_key_len

    def calc_prfplus(self, prf, key, seed, length):
        r = b''
        t = None
        x = 1
        while len(r) < length and x < 255:
            if t is not None:
                s = t
            else:
                s = b''
            s = s + seed + bytes([x])
            t = self.calc_prf(prf, key, s)
            r = r + t
            x = x + 1

        if x == 255:
            return None
        return r

    def calc_prf(self, prf, key, data):
        h = self.ike_integ_alg.mac(key, prf, backend=default_backend())
        h.update(data)
        return h.finalize()

    def calc_keys(self):
        prf = self.ike_prf_alg.mod()
        # SKEYSEED = prf(Ni | Nr, g^ir)
        s = self.i_nonce + self.r_nonce
        self.skeyseed = self.calc_prf(prf, s, self.dh_shared_secret)

        # calculate S = Ni | Nr | SPIi SPIr
        s = s + self.ispi + self.rspi

        prf_key_trunc = self.ike_prf_alg.trunc_len
        encr_key_len = self.ike_crypto_key_len
        tr_prf_key_len = self.ike_prf_alg.key_len
        integ_key_len = self.ike_integ_alg.key_len
        l = (prf_key_trunc +
             integ_key_len * 2 +
             encr_key_len * 2 +
             tr_prf_key_len * 2)
        keymat = self.calc_prfplus(prf, self.skeyseed, s, l)

        pos = 0
        self.sk_d = keymat[:pos+prf_key_trunc]
        pos += prf_key_trunc

        self.sk_ai = keymat[pos:pos+integ_key_len]
        pos += integ_key_len
        self.sk_ar = keymat[pos:pos+integ_key_len]
        pos += integ_key_len

        self.sk_ei = keymat[pos:pos+encr_key_len]
        pos += encr_key_len
        self.sk_er = keymat[pos:pos+encr_key_len]
        pos += encr_key_len

        self.sk_pi = keymat[pos:pos+tr_prf_key_len]
        pos += tr_prf_key_len
        self.sk_pr = keymat[pos:pos+tr_prf_key_len]

    def generate_authmsg(self, prf, packet):
        if self.is_initiator:
            id = self.i_id
            nonce = self.r_nonce
            key = self.sk_pi
        data = bytes([self.id_type, 0, 0, 0]) + id
        id_hash = self.calc_prf(prf, key, data)
        return packet + nonce + id_hash

    def auth_init(self):
        prf = self.ike_prf_alg.mod()
        authmsg = self.generate_authmsg(prf, raw(self.init_req_packet))
        psk = self.calc_prf(prf, self.auth_data, KEY_PAD)
        self.auth_data = self.calc_prf(prf, psk, authmsg)

    def encrypt(self, data):
        data = self.ike_crypto_alg.pad(data)
        return self.ike_crypto_alg.encrypt(data, self.my_cryptokey)

    @property
    def peer_authkey(self):
        if self.is_initiator:
            return self.sk_ar
        return self.sk_ai

    @property
    def my_authkey(self):
        if self.is_initiator:
            return self.sk_ai
        return self.sk_ar

    @property
    def my_cryptokey(self):
        if self.is_initiator:
            return self.sk_ei
        return self.sk_er

    @property
    def peer_cryptokey(self):
        if self.is_initiator:
            return self.sk_er
        return self.sk_ei

    def verify_hmac(self, ikemsg):
        integ_trunc = self.ike_integ_alg.trunc_len
        exp_hmac = ikemsg[-integ_trunc:]
        data = ikemsg[:-integ_trunc]
        computed_hmac = self.compute_hmac(self.ike_integ_alg.mod(),
                                          self.peer_authkey, data)
        self.test.assertEqual(computed_hmac[:integ_trunc], exp_hmac)

    def compute_hmac(self, integ, key, data):
        h = self.ike_integ_alg.mac(key, integ, backend=default_backend())
        h.update(data)
        return h.finalize()

    def decrypt(self, data):
        return self.ike_crypto_alg.decrypt(data, self.peer_cryptokey)

    def hmac_and_decrypt(self, ike):
        ep = ike[ikev2.IKEv2_payload_Encrypted]
        self.verify_hmac(raw(ike))
        integ_trunc = self.ike_integ_alg.trunc_len

        # remove ICV and decrypt payload
        ct = ep.load[:-integ_trunc]
        return self.decrypt(ct)

    def generate_ts(self):
        c = self.child_sas[0]
        ts1 = ikev2.IPv4TrafficSelector(
                IP_protocol_ID=0,
                starting_address_v4=c.local_ts['start_addr'],
                ending_address_v4=c.local_ts['end_addr'])
        ts2 = ikev2.IPv4TrafficSelector(
                IP_protocol_ID=0,
                starting_address_v4=c.remote_ts['start_addr'],
                ending_address_v4=c.remote_ts['end_addr'])
        return ([ts1], [ts2])

    def set_ike_props(self, crypto, crypto_key_len, integ, prf, dh):
        if crypto not in CRYPTO_ALGOS:
            raise TypeError('unsupported encryption algo %r' % crypto)
        self.ike_crypto = crypto
        self.ike_crypto_alg = CRYPTO_ALGOS[crypto]
        self.ike_crypto_key_len = crypto_key_len

        if integ not in AUTH_ALGOS:
            raise TypeError('unsupported auth algo %r' % integ)
        self.ike_integ = integ
        self.ike_integ_alg = AUTH_ALGOS[integ]

        if prf not in PRF_ALGOS:
            raise TypeError('unsupported prf algo %r' % prf)
        self.ike_prf = prf
        self.ike_prf_alg = PRF_ALGOS[prf]
        self.ike_dh = dh
        self.ike_group = DH[self.ike_dh]

    def set_esp_props(self, crypto, crypto_key_len, integ):
        self.esp_crypto_key_len = crypto_key_len
        if crypto not in CRYPTO_ALGOS:
            raise TypeError('unsupported encryption algo %r' % crypto)
        self.esp_crypto = crypto
        self.esp_crypto_alg = CRYPTO_ALGOS[crypto]

        if integ not in AUTH_ALGOS:
            raise TypeError('unsupported auth algo %r' % integ)
        self.esp_integ = integ
        self.esp_integ_alg = AUTH_ALGOS[integ]

    def crypto_attr(self, key_len):
        if self.ike_crypto in ['AES-CBC', 'AES-GCM']:
            return (0x800e << 16 | key_len << 3, 12)
        else:
            raise Exception('unsupported attribute type')

    def ike_crypto_attr(self):
        return self.crypto_attr(self.ike_crypto_key_len)

    def esp_crypto_attr(self):
        return self.crypto_attr(self.esp_crypto_key_len)


class TestResponder(VppTestCase):
    """ responder test """

    @classmethod
    def setUpClass(cls):
        import scapy.contrib.ikev2 as _ikev2
        globals()['ikev2'] = _ikev2
        super(TestResponder, cls).setUpClass()
        cls.create_pg_interfaces(range(2))
        for i in cls.pg_interfaces:
            i.admin_up()
            i.config_ip4()
            i.resolve_arp()

    @classmethod
    def tearDownClass(cls):
        super(TestResponder, cls).tearDownClass()

    def setUp(self):
        super(TestResponder, self).setUp()
        self.config_tc()

    def config_tc(self):
        self.p = Profile(self, 'pr1')
        self.p.add_auth(method='shared-key', data=b'$3cr3tpa$$w0rd')
        self.p.add_local_id(id_type='fqdn', data=b'vpp.home')
        self.p.add_remote_id(id_type='fqdn', data=b'roadwarrior.example.com')
        self.p.add_local_ts(start_addr=0x0a0a0a0, end_addr=0x0a0a0aff)
        self.p.add_remote_ts(start_addr=0xa000000, end_addr=0xa0000ff)
        self.p.add_vpp_config()

        self.sa = IKEv2SA(self, id=self.p.remote_id['data'], is_initiator=True,
                          auth_data=self.p.auth['data'],
                          id_type=self.p.local_id['id_type'],
                          local_ts=self.p.remote_ts, remote_ts=self.p.local_ts)

        self.sa.set_ike_props(crypto='AES-CBC', crypto_key_len=32,
                              integ='HMAC-SHA1-96', prf='PRF_HMAC_SHA2_256',
                              dh='2048MODPgr')
        self.sa.set_esp_props(crypto='AES-CBC', crypto_key_len=32,
                              integ='HMAC-SHA1-96')
        self.sa.generate_dh_data()

    def create_ike_msg(self, src_if, msg, sport=500, dport=500):
        return (Ether(dst=src_if.local_mac, src=src_if.remote_mac) /
                IP(src=src_if.remote_ip4, dst=src_if.local_ip4) /
                UDP(sport=sport, dport=dport) / msg)

    def send_sa_init(self):
        tr_attr = self.sa.ike_crypto_attr()
        trans = (ikev2.IKEv2_payload_Transform(transform_type='Encryption',
                 transform_id=self.sa.ike_crypto, length=tr_attr[1],
                 key_length=tr_attr[0]) /
                 ikev2.IKEv2_payload_Transform(transform_type='Integrity',
                 transform_id=self.sa.ike_integ) /
                 ikev2.IKEv2_payload_Transform(transform_type='PRF',
                 transform_id=self.sa.ike_prf_alg.name) /
                 ikev2.IKEv2_payload_Transform(transform_type='GroupDesc',
                 transform_id=self.sa.ike_dh))

        props = (ikev2.IKEv2_payload_Proposal(proposal=1, proto='IKEv2',
                 trans_nb=4, trans=trans))

        self.sa.init_req_packet = (
                ikev2.IKEv2(init_SPI=self.sa.ispi,
                            flags='Initiator', exch_type='IKE_SA_INIT') /
                ikev2.IKEv2_payload_SA(next_payload='KE', prop=props) /
                ikev2.IKEv2_payload_KE(next_payload='Nonce',
                                       group=self.sa.ike_dh,
                                       load=self.sa.dh_pub_key()) /
                ikev2.IKEv2_payload_Nonce(load=self.sa.i_nonce))

        ike_msg = self.create_ike_msg(self.pg0, self.sa.init_req_packet)
        self.pg0.add_stream(ike_msg)
        self.pg0.enable_capture()
        self.pg_start()
        capture = self.pg0.get_capture(1)
        self.verify_sa_init(capture[0])

    def send_sa_auth(self):
        tr_attr = self.sa.esp_crypto_attr()
        trans = (ikev2.IKEv2_payload_Transform(transform_type='Encryption',
                 transform_id=self.sa.esp_crypto, length=tr_attr[1],
                 key_length=tr_attr[0]) /
                 ikev2.IKEv2_payload_Transform(transform_type='Integrity',
                 transform_id=self.sa.esp_integ) /
                 ikev2.IKEv2_payload_Transform(
                 transform_type='Extended Sequence Number',
                 transform_id='No ESN') /
                 ikev2.IKEv2_payload_Transform(
                 transform_type='Extended Sequence Number',
                 transform_id='ESN'))

        props = (ikev2.IKEv2_payload_Proposal(proposal=1, proto='ESP',
                 SPIsize=4, SPI=os.urandom(4), trans_nb=4, trans=trans))

        tsi, tsr = self.sa.generate_ts()
        plain = (ikev2.IKEv2_payload_IDi(next_payload='AUTH',
                 IDtype=self.sa.id_type, load=self.sa.i_id) /
                 ikev2.IKEv2_payload_AUTH(next_payload='SA',
                 auth_type=2, load=self.sa.auth_data) /
                 ikev2.IKEv2_payload_SA(next_payload='TSi', prop=props) /
                 ikev2.IKEv2_payload_TSi(next_payload='TSr',
                 number_of_TSs=len(tsi),
                 traffic_selector=tsi) /
                 ikev2.IKEv2_payload_TSr(next_payload='Notify',
                 number_of_TSs=len(tsr),
                 traffic_selector=tsr) /
                 ikev2.IKEv2_payload_Notify(type='INITIAL_CONTACT'))
        encr = self.sa.encrypt(raw(plain))

        trunc_len = self.sa.ike_integ_alg.trunc_len
        plen = len(encr) + len(ikev2.IKEv2_payload_Encrypted()) + trunc_len
        tlen = plen + len(ikev2.IKEv2())

        sk_p = ikev2.IKEv2_payload_Encrypted(next_payload='IDi',
                                             length=plen, load=encr)
        sa_auth = (ikev2.IKEv2(init_SPI=self.sa.ispi, resp_SPI=self.sa.rspi,
                   length=tlen, flags='Initiator', exch_type='IKE_AUTH', id=1))
        sa_auth /= sk_p

        integ_data = raw(sa_auth)
        hmac_data = self.sa.compute_hmac(self.sa.ike_integ_alg.mod(),
                                         self.sa.my_authkey, integ_data)
        sa_auth = sa_auth / Raw(hmac_data[:trunc_len])
        assert(len(sa_auth) == tlen)

        packet = self.create_ike_msg(self.pg0, sa_auth)
        self.pg0.add_stream(packet)
        self.pg0.enable_capture()
        self.pg_start()
        capture = self.pg0.get_capture(1)
        self.verify_sa_auth(capture[0])

    def verify_sa_init(self, packet):
        ih = packet[ikev2.IKEv2]
        self.assertEqual(ih.exch_type, 34)
        self.assertTrue('Response' in ih.flags)
        self.assertEqual(ih.init_SPI, self.sa.ispi)
        self.assertNotEqual(ih.resp_SPI, 0)
        self.sa.rspi = ih.resp_SPI
        try:
            sa = ih[ikev2.IKEv2_payload_SA]
            self.sa.r_nonce = ih[ikev2.IKEv2_payload_Nonce].load
            self.sa.r_dh_data = ih[ikev2.IKEv2_payload_KE].load
        except AttributeError as e:
            self.logger.error("unexpected reply: SA/Nonce/KE payload found!")
            raise
        self.sa.complete_dh_data()
        self.sa.calc_keys()
        self.sa.auth_init()

    def verify_sa_auth(self, packet):
        try:
            ike = packet[ikev2.IKEv2]
            ep = packet[ikev2.IKEv2_payload_Encrypted]
        except KeyError as e:
            self.logger.error("unexpected reply: no IKEv2/Encrypt payload!")
            raise
        plain = self.sa.hmac_and_decrypt(ike)
        self.sa.calc_child_keys()

    def verify_child_sas(self):
        sas = self.vapi.ipsec_sa_dump()
        self.assertEqual(len(sas), 2)
        sa0 = sas[0].entry
        sa1 = sas[1].entry
        c = self.sa.child_sas[0]

        # verify crypto keys
        self.assertEqual(sa0.crypto_key.length, len(c.sk_er))
        self.assertEqual(sa1.crypto_key.length, len(c.sk_ei))
        self.assertEqual(sa0.crypto_key.data[:len(c.sk_er)], c.sk_er)
        self.assertEqual(sa1.crypto_key.data[:len(c.sk_ei)], c.sk_ei)

        # verify integ keys
        self.assertEqual(sa0.integrity_key.length, len(c.sk_ar))
        self.assertEqual(sa1.integrity_key.length, len(c.sk_ai))
        self.assertEqual(sa0.integrity_key.data[:len(c.sk_ar)], c.sk_ar)
        self.assertEqual(sa1.integrity_key.data[:len(c.sk_ai)], c.sk_ai)

    def test_responder(self):
        self.send_sa_init()
        self.send_sa_auth()
        self.verify_child_sas()


if __name__ == '__main__':
    unittest.main(testRunner=VppTestRunner)