| diff --git a/scapy/layers/ipsec.py b/scapy/layers/ipsec.py |
| index f8c601fa..f566d288 100644 |
| --- a/scapy/layers/ipsec.py |
| +++ b/scapy/layers/ipsec.py |
| @@ -138,6 +138,7 @@ 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 +359,8 @@ 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: |
| @@ -401,12 +398,7 @@ 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: |
| @@ -545,7 +537,7 @@ 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. |
| |
| @@ -561,16 +553,20 @@ 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. |
| |
| @@ -602,6 +598,8 @@ 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 |
| @@ -864,6 +862,23 @@ 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' % |
| @@ -877,7 +892,8 @@ 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() |
| @@ -901,7 +917,7 @@ 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() |
| @@ -928,7 +944,8 @@ 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: |
| @@ -968,7 +985,8 @@ 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: |
| @@ -1005,11 +1023,12 @@ 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 |
| @@ -1050,11 +1069,12 @@ 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 |
| |
| |