diff --git a/scapy/layers/ipsec.py b/scapy/layers/ipsec.py index ae057ee1..d7a21e8b 100644 --- a/scapy/layers/ipsec.py +++ b/scapy/layers/ipsec.py @@ -56,6 +56,7 @@ from scapy.fields import ByteEnumField, ByteField, IntField, PacketField, \ ShortField, StrField, XIntField, XStrField, XStrLenField from scapy.packet import Packet, bind_layers, Raw from scapy.layers.inet import IP, UDP +from scapy.contrib.mpls import MPLS import scapy.modules.six as six from scapy.modules.six.moves import range from scapy.layers.inet6 import IPv6, IPv6ExtHdrHopByHop, IPv6ExtHdrDestOpt, \ @@ -138,6 +139,7 @@ bind_layers(IP, ESP, proto=socket.IPPROTO_ESP) bind_layers(IPv6, ESP, nh=socket.IPPROTO_ESP) bind_layers(UDP, ESP, dport=4500) # NAT-Traversal encapsulation bind_layers(UDP, ESP, sport=4500) # NAT-Traversal encapsulation +bind_layers(UDP, ESP, dport=4545) # NAT-Traversal encapsulation - random port ############################################################################### @@ -359,11 +361,8 @@ class CryptAlgo(object): encryptor = cipher.encryptor() if self.is_aead: - if esn_en: - aad = struct.pack('!LLL', esp.spi, esn, esp.seq) - else: - aad = struct.pack('!LL', esp.spi, esp.seq) - encryptor.authenticate_additional_data(aad) + encryptor.authenticate_additional_data(sa.build_aead(esp)) + data = encryptor.update(data) + encryptor.finalize() data += encryptor.tag[:self.icv_size] else: @@ -400,12 +399,7 @@ class CryptAlgo(object): if self.is_aead: # Tag value check is done during the finalize method - if esn_en: - decryptor.authenticate_additional_data( - struct.pack('!LLL', esp.spi, esn, esp.seq)) - else: - decryptor.authenticate_additional_data( - struct.pack('!LL', esp.spi, esp.seq)) + decryptor.authenticate_additional_data(sa.build_aead(esp)) try: data = decryptor.update(data) + decryptor.finalize() except InvalidTag as err: @@ -445,6 +439,7 @@ if algorithms: CRYPT_ALGOS['AES-CTR'] = CryptAlgo('AES-CTR', cipher=algorithms.AES, mode=modes.CTR, + block_size=1, iv_size=8, salt_size=4, format_mode_iv=_aes_ctr_format_mode_iv) @@ -452,6 +447,7 @@ if algorithms: CRYPT_ALGOS['AES-GCM'] = CryptAlgo('AES-GCM', cipher=algorithms.AES, mode=modes.GCM, + block_size=1, salt_size=4, iv_size=8, icv_size=16, @@ -460,6 +456,7 @@ if algorithms: CRYPT_ALGOS['AES-CCM'] = CryptAlgo('AES-CCM', cipher=algorithms.AES, mode=modes.CCM, + block_size=1, iv_size=8, salt_size=3, icv_size=16, @@ -544,7 +541,7 @@ class AuthAlgo(object): else: return self.mac(key, self.digestmod(), default_backend()) - def sign(self, pkt, key): + def sign(self, pkt, key, trailer=None): """ Sign an IPsec (ESP or AH) packet with this algo. @@ -560,16 +557,20 @@ class AuthAlgo(object): if pkt.haslayer(ESP): mac.update(raw(pkt[ESP])) + if trailer: + mac.update(trailer) pkt[ESP].data += mac.finalize()[:self.icv_size] elif pkt.haslayer(AH): clone = zero_mutable_fields(pkt.copy(), sending=True) mac.update(raw(clone)) + if trailer: + mac.update(trailer) pkt[AH].icv = mac.finalize()[:self.icv_size] return pkt - def verify(self, pkt, key): + def verify(self, pkt, key, trailer): """ Check that the integrity check value (icv) of a packet is valid. @@ -600,6 +601,8 @@ class AuthAlgo(object): clone = zero_mutable_fields(pkt.copy(), sending=False) mac.update(raw(clone)) + if trailer: + mac.update(trailer) # bytearray(4)) #raw(trailer)) computed_icv = mac.finalize()[:self.icv_size] # XXX: Cannot use mac.verify because the ICV can be truncated @@ -788,7 +791,7 @@ class SecurityAssociation(object): This class is responsible of "encryption" and "decryption" of IPsec packets. # noqa: E501 """ - SUPPORTED_PROTOS = (IP, IPv6) + SUPPORTED_PROTOS = (IP, IPv6, MPLS) def __init__(self, proto, spi, seq_num=1, crypt_algo=None, crypt_key=None, auth_algo=None, auth_key=None, tunnel_header=None, nat_t_header=None, esn_en=False, esn=0): # noqa: E501 @@ -862,6 +865,23 @@ class SecurityAssociation(object): raise TypeError('nat_t_header must be %s' % UDP.name) self.nat_t_header = nat_t_header + def build_aead(self, esp): + if self.esn_en: + return (struct.pack('!LLL', esp.spi, self.seq_num >> 32, esp.seq)) + else: + return (struct.pack('!LL', esp.spi, esp.seq)) + + def build_seq_num(self, num): + # only lower order bits are transmitted + # higher order bits are used in the ICV + lower = num & 0xffffffff + upper = num >> 32 + + if self.esn_en: + return lower, struct.pack("!I", upper) + else: + return lower, None + def check_spi(self, pkt): if pkt.spi != self.spi: raise TypeError('packet spi=0x%x does not match the SA spi=0x%x' % @@ -875,7 +895,8 @@ class SecurityAssociation(object): if len(iv) != self.crypt_algo.iv_size: raise TypeError('iv length must be %s' % self.crypt_algo.iv_size) # noqa: E501 - esp = _ESPPlain(spi=self.spi, seq=seq_num or self.seq_num, iv=iv) + low_seq_num, high_seq_num = self.build_seq_num(seq_num or self.seq_num) + esp = _ESPPlain(spi=self.spi, seq=low_seq_num, iv=iv) if self.tunnel_header: tunnel = self.tunnel_header.copy() @@ -899,7 +920,7 @@ class SecurityAssociation(object): esn_en=esn_en or self.esn_en, esn=esn or self.esn) - self.auth_algo.sign(esp, self.auth_key) + self.auth_algo.sign(esp, self.auth_key, high_seq_num) if self.nat_t_header: nat_t_header = self.nat_t_header.copy() @@ -926,7 +947,8 @@ class SecurityAssociation(object): def _encrypt_ah(self, pkt, seq_num=None): - ah = AH(spi=self.spi, seq=seq_num or self.seq_num, + low_seq_num, high_seq_num = self.build_seq_num(seq_num or self.seq_num) + ah = AH(spi=self.spi, seq=low_seq_num, icv=b"\x00" * self.auth_algo.icv_size) if self.tunnel_header: @@ -966,7 +988,8 @@ class SecurityAssociation(object): else: ip_header.plen = len(ip_header.payload) + len(ah) + len(payload) - signed_pkt = self.auth_algo.sign(ip_header / ah / payload, self.auth_key) # noqa: E501 + signed_pkt = self.auth_algo.sign(ip_header / ah / payload, + self.auth_key, high_seq_num) # noqa: E501 # sequence number must always change, unless specified by the user if seq_num is None: @@ -1003,11 +1026,12 @@ class SecurityAssociation(object): def _decrypt_esp(self, pkt, verify=True, esn_en=None, esn=None): + low_seq_num, high_seq_num = self.build_seq_num(self.seq_num) encrypted = pkt[ESP] if verify: self.check_spi(pkt) - self.auth_algo.verify(encrypted, self.auth_key) + self.auth_algo.verify(encrypted, self.auth_key, high_seq_num) esp = self.crypt_algo.decrypt(self, encrypted, self.crypt_key, self.crypt_algo.icv_size or @@ -1048,9 +1072,10 @@ class SecurityAssociation(object): def _decrypt_ah(self, pkt, verify=True): + low_seq_num, high_seq_num = self.build_seq_num(self.seq_num) if verify: self.check_spi(pkt) - self.auth_algo.verify(pkt, self.auth_key) + self.auth_algo.verify(pkt, self.auth_key, high_seq_num) ah = pkt[AH] payload = ah.payload