Tools like tcpdump and wireshark can parse the TCP Authentication Option but there is not yet support to verify correct signatures.
This patch implements TCP-AO signature verification using scapy and the python cryptography package.
The python code is verified itself with a subset of IETF test vectors from this page: https://datatracker.ietf.org/doc/html/draft-touch-tcpm-ao-test-vectors-02
The code in this commit is not specific to linux
Signed-off-by: Leonard Crestez cdleonard@gmail.com --- .../tcp_authopt_test/scapy_tcp_authopt.py | 220 +++++++++++ .../tcp_authopt_test/scapy_utils.py | 177 +++++++++ .../tcp_authopt_test/test_vectors.py | 365 ++++++++++++++++++ .../tcp_authopt/tcp_authopt_test/validator.py | 138 +++++++ 4 files changed, 900 insertions(+) create mode 100644 tools/testing/selftests/tcp_authopt/tcp_authopt_test/scapy_tcp_authopt.py create mode 100644 tools/testing/selftests/tcp_authopt/tcp_authopt_test/scapy_utils.py create mode 100644 tools/testing/selftests/tcp_authopt/tcp_authopt_test/test_vectors.py create mode 100644 tools/testing/selftests/tcp_authopt/tcp_authopt_test/validator.py
diff --git a/tools/testing/selftests/tcp_authopt/tcp_authopt_test/scapy_tcp_authopt.py b/tools/testing/selftests/tcp_authopt/tcp_authopt_test/scapy_tcp_authopt.py new file mode 100644 index 000000000000..ce36321b803a --- /dev/null +++ b/tools/testing/selftests/tcp_authopt/tcp_authopt_test/scapy_tcp_authopt.py @@ -0,0 +1,220 @@ +# SPDX-License-Identifier: GPL-2.0 +"""Packet-processing utilities implementing RFC5925 and RFC2926""" + +import hmac +import logging +import struct + +from scapy.layers.inet import TCP +from scapy.packet import Packet + +from .scapy_utils import ( + TCPOPT_AUTHOPT, + IPvXAddress, + get_packet_ipvx_dst, + get_packet_ipvx_src, + get_tcp_doff, + get_tcp_pseudoheader, +) + +logger = logging.getLogger(__name__) + + +def _cmac_aes_digest(key: bytes, msg: bytes) -> bytes: + from cryptography.hazmat.backends import default_backend + from cryptography.hazmat.primitives import cmac + from cryptography.hazmat.primitives.ciphers import algorithms + + backend = default_backend() + c = cmac.CMAC(algorithms.AES(key), backend=backend) + c.update(bytes(msg)) + return c.finalize() + + +class TcpAuthOptAlg: + @classmethod + def kdf(cls, master_key: bytes, context: bytes) -> bytes: + raise NotImplementedError() + + @classmethod + def mac(cls, traffic_key: bytes, message: bytes) -> bytes: + raise NotImplementedError() + + maclen = -1 + + +class TcpAuthOptAlg_HMAC_SHA1(TcpAuthOptAlg): + @classmethod + def kdf(cls, master_key: bytes, context: bytes) -> bytes: + input = b"\x01" + b"TCP-AO" + context + b"\x00\xa0" + return hmac.digest(master_key, input, "SHA1") + + @classmethod + def mac(cls, traffic_key: bytes, message: bytes) -> bytes: + return hmac.digest(traffic_key, message, "SHA1")[:12] + + maclen = 12 + + +class TcpAuthOptAlg_CMAC_AES(TcpAuthOptAlg): + @classmethod + def kdf(self, master_key: bytes, context: bytes) -> bytes: + if len(master_key) == 16: + key = master_key + else: + key = _cmac_aes_digest(b"\x00" * 16, master_key) + return _cmac_aes_digest(key, b"\x01" + b"TCP-AO" + context + b"\x00\x80") + + @classmethod + def mac(self, traffic_key: bytes, message: bytes) -> bytes: + return _cmac_aes_digest(traffic_key, message)[:12] + + maclen = 12 + + +def get_alg(name: str) -> TcpAuthOptAlg: + if name.upper() == "HMAC-SHA-1-96": + return TcpAuthOptAlg_HMAC_SHA1() + elif name.upper() == "AES-128-CMAC-96": + return TcpAuthOptAlg_CMAC_AES() + else: + raise ValueError(f"Bad TCP AuthOpt algorithms {name}") + + +def build_context( + saddr: IPvXAddress, daddr: IPvXAddress, sport, dport, src_isn, dst_isn +) -> bytes: + """Build context bytes as specified by RFC5925 section 5.2""" + return ( + saddr.packed + + daddr.packed + + struct.pack( + "!HHII", + sport, + dport, + src_isn, + dst_isn, + ) + ) + + +def build_context_from_packet(p: Packet, src_isn: int, dst_isn: int) -> bytes: + """Build context based on a scapy Packet and src/dst initial-sequence numbers""" + return build_context( + get_packet_ipvx_src(p), + get_packet_ipvx_dst(p), + p[TCP].sport, + p[TCP].dport, + src_isn, + dst_isn, + ) + + +def build_message_from_packet(p: Packet, include_options=True, sne=0) -> bytearray: + """Build message bytes as described by RFC5925 section 5.1""" + result = bytearray() + result += struct.pack("!I", sne) + th = p[TCP] + + # ip pseudo-header: + result += get_tcp_pseudoheader(th) + + # tcp header with checksum set to zero + th_bytes = bytes(p[TCP]) + result += th_bytes[:16] + result += b"\x00\x00" + result += th_bytes[18:20] + + # Even if include_options=False the TCP-AO option itself is still included + # with the MAC set to all-zeros. This means we need to parse TCP options. + pos = 20 + tcphdr_optend = get_tcp_doff(th) * 4 + # logger.info("th_bytes: %s", th_bytes.hex(' ')) + assert len(th_bytes) >= tcphdr_optend + while pos < tcphdr_optend: + optnum = th_bytes[pos] + pos += 1 + if optnum == 0 or optnum == 1: + if include_options: + result += bytes([optnum]) + continue + + optlen = th_bytes[pos] + pos += 1 + if pos + optlen - 2 > tcphdr_optend: + logger.info( + "bad tcp option %d optlen %d beyond end-of-header", optnum, optlen + ) + break + if optlen < 2: + logger.info("bad tcp option %d optlen %d less than two", optnum, optlen) + break + if optnum == TCPOPT_AUTHOPT: + if optlen < 4: + logger.info("bad tcp option %d optlen %d", optnum, optlen) + break + result += bytes([optnum, optlen]) + result += th_bytes[pos : pos + 2] + result += (optlen - 4) * b"\x00" + elif include_options: + result += bytes([optnum, optlen]) + result += th_bytes[pos : pos + optlen - 2] + pos += optlen - 2 + result += bytes(p[TCP].payload) + return result + + +def check_tcp_authopt_signature( + p: Packet, alg: TcpAuthOptAlg, master_key, sisn, disn, include_options=True, sne=0 +): + from .scapy_utils import scapy_tcp_get_authopt_val + + ao = scapy_tcp_get_authopt_val(p[TCP]) + if ao is None: + return None + + context_bytes = build_context_from_packet(p, sisn, disn) + traffic_key = alg.kdf(master_key, context_bytes) + message_bytes = build_message_from_packet( + p, include_options=include_options, sne=sne + ) + mac = alg.mac(traffic_key, message_bytes) + return mac == ao.mac + + +def add_tcp_authopt_signature( + p: Packet, + alg: TcpAuthOptAlg, + master_key, + sisn, + disn, + keyid=0, + rnextkeyid=0, + include_options=True, + sne=0, +): + """Sign a packet""" + th = p[TCP] + keyids = struct.pack("BB", keyid, rnextkeyid) + th.options = th.options + [(TCPOPT_AUTHOPT, keyids + alg.maclen * b"\x00")] + + context_bytes = build_context_from_packet(p, sisn, disn) + traffic_key = alg.kdf(master_key, context_bytes) + message_bytes = build_message_from_packet( + p, include_options=include_options, sne=sne + ) + mac = alg.mac(traffic_key, message_bytes) + th.options[-1] = (TCPOPT_AUTHOPT, keyids + mac) + + +def break_tcp_authopt_signature(packet: Packet): + """Invalidate TCP-AO signature inside a packet + + The packet must already be signed and it gets modified in-place. + """ + opt = packet[TCP].options[-1] + if opt[0] != TCPOPT_AUTHOPT: + raise ValueError("TCP option list must end with TCP_AUTHOPT") + opt_mac = bytearray(opt[1]) + opt_mac[-1] ^= 0xFF + packet[TCP].options[-1] = (opt[0], bytes(opt_mac)) diff --git a/tools/testing/selftests/tcp_authopt/tcp_authopt_test/scapy_utils.py b/tools/testing/selftests/tcp_authopt/tcp_authopt_test/scapy_utils.py new file mode 100644 index 000000000000..03c843b8378e --- /dev/null +++ b/tools/testing/selftests/tcp_authopt/tcp_authopt_test/scapy_utils.py @@ -0,0 +1,177 @@ +# SPDX-License-Identifier: GPL-2.0 +import socket +import struct +import threading +import typing +from dataclasses import dataclass +from ipaddress import IPv4Address, IPv6Address + +from scapy.config import conf as scapy_conf +from scapy.layers.inet import IP, TCP +from scapy.layers.inet6 import IPv6 +from scapy.packet import Packet +from scapy.sendrecv import AsyncSniffer + +from .utils import netns_context + +# TCPOPT numbers are apparently not available in scapy +TCPOPT_MD5SIG = 19 +TCPOPT_AUTHOPT = 29 + +# Easy generic handling of IPv4/IPv6Address +IPvXAddress = typing.Union[IPv4Address, IPv6Address] + + +def get_packet_ipvx_src(p: Packet) -> IPvXAddress: + if IP in p: + return IPv4Address(p[IP].src) + elif IPv6 in p: + return IPv6Address(p[IPv6].src) + else: + raise Exception("Neither IP nor IPv6 found on packet") + + +def get_packet_ipvx_dst(p: Packet) -> IPvXAddress: + if IP in p: + return IPv4Address(p[IP].dst) + elif IPv6 in p: + return IPv6Address(p[IPv6].dst) + else: + raise Exception("Neither IP nor IPv6 found on packet") + + +def get_tcp_doff(th: TCP): + """Get the TCP data offset, even if packet is not yet built""" + doff = th.dataofs + if doff is None: + opt_len = len(th.get_field("options").i2m(th, th.options)) + doff = 5 + ((opt_len + 3) // 4) + return doff + + +def get_tcp_v4_pseudoheader(tcp_packet: TCP) -> bytes: + iph = tcp_packet.underlayer + return struct.pack( + "!4s4sHH", + IPv4Address(iph.src).packed, + IPv4Address(iph.dst).packed, + socket.IPPROTO_TCP, + get_tcp_doff(tcp_packet) * 4 + len(tcp_packet.payload), + ) + + +def get_tcp_v6_pseudoheader(tcp_packet: TCP) -> bytes: + ipv6 = tcp_packet.underlayer + return struct.pack( + "!16s16sII", + IPv6Address(ipv6.src).packed, + IPv6Address(ipv6.dst).packed, + get_tcp_doff(tcp_packet) * 4 + len(tcp_packet.payload), + socket.IPPROTO_TCP, + ) + + +def get_tcp_pseudoheader(tcp_packet: TCP): + if isinstance(tcp_packet.underlayer, IP): + return get_tcp_v4_pseudoheader(tcp_packet) + if isinstance(tcp_packet.underlayer, IPv6): + return get_tcp_v6_pseudoheader(tcp_packet) + raise ValueError("TCP underlayer is neither IP nor IPv6") + + +def tcp_seq_wrap(seq): + return seq & 0xFFFFFFFF + + +@dataclass +class tcphdr_authopt: + """Representation of a TCP auth option as it appears in a TCP packet""" + + keyid: int + rnextkeyid: int + mac: bytes + + @classmethod + def unpack(cls, buf) -> "tcphdr_authopt": + return cls(buf[0], buf[1], buf[2:]) + + def __repr__(self): + return f"tcphdr_authopt({self.keyid}, {self.rnextkeyid}, bytes.fromhex({self.mac.hex(' ')!r})" + + +def scapy_tcp_get_authopt_val(tcp) -> typing.Optional[tcphdr_authopt]: + for optnum, optval in tcp.options: + if optnum == TCPOPT_AUTHOPT: + return tcphdr_authopt.unpack(optval) + return None + + +def scapy_tcp_get_md5_sig(tcp) -> typing.Optional[bytes]: + """Return the MD5 signature (as bytes) or None""" + for optnum, optval in tcp.options: + if optnum == TCPOPT_MD5SIG: + return optval + return None + + +def calc_tcp_md5_hash(p, key: bytes) -> bytes: + """Calculate TCP-MD5 hash from packet and return a 16-byte string""" + import hashlib + + h = hashlib.md5() + tp = p[TCP] + th_bytes = bytes(p[TCP]) + h.update(get_tcp_pseudoheader(tp)) + h.update(th_bytes[:16]) + h.update(b"\x00\x00") + h.update(th_bytes[18:20]) + h.update(bytes(tp.payload)) + h.update(key) + + return h.digest() + + +def create_l2socket(ns: str = "", **kw): + """Create a scapy L2socket inside a namespace""" + + with netns_context(ns): + return scapy_conf.L2socket(**kw) + + +def create_capture_socket(ns: str = "", **kw): + """Create a scapy L2listen socket inside a namespace""" + from scapy.config import conf as scapy_conf + + with netns_context(ns): + return scapy_conf.L2listen(**kw) + + +def scapy_sniffer_start_block(sniffer: AsyncSniffer, timeout=1): + """Like AsyncSniffer.start except block until sniffing starts + + This ensures no lost packets and no delays + """ + if sniffer.kwargs.get("started_callback"): + raise ValueError("sniffer must not already have a started_callback") + + e = threading.Event() + sniffer.kwargs["started_callback"] = e.set + sniffer.start() + e.wait(timeout=timeout) + if not e.is_set(): + raise TimeoutError("Timed out waiting for sniffer to start") + + +def scapy_sniffer_stop(sniffer: AsyncSniffer): + """Like AsyncSniffer.stop except no error is raising if not running""" + if sniffer is not None and sniffer.running: + sniffer.stop() + + +class AsyncSnifferContext(AsyncSniffer): + def __enter__(self): + scapy_sniffer_start_block(self) + return self + + def __exit__(self, *a): + scapy_sniffer_stop(self) diff --git a/tools/testing/selftests/tcp_authopt/tcp_authopt_test/test_vectors.py b/tools/testing/selftests/tcp_authopt/tcp_authopt_test/test_vectors.py new file mode 100644 index 000000000000..e0fcde04629c --- /dev/null +++ b/tools/testing/selftests/tcp_authopt/tcp_authopt_test/test_vectors.py @@ -0,0 +1,365 @@ +# SPDX-License-Identifier: GPL-2.0 +import logging +import socket +from ipaddress import IPv4Address, IPv6Address + +from scapy.layers.inet import IP, TCP +from scapy.layers.inet6 import IPv6 + +from .scapy_tcp_authopt import ( + build_context_from_packet, + build_message_from_packet, + get_alg, +) +from .scapy_utils import scapy_tcp_get_authopt_val + +logger = logging.getLogger(__name__) + + +class TestIETFVectors: + """Test python implementation of TCP-AO algorithms + + Data is a subset of IETF test vectors: + https://datatracker.ietf.org/doc/html/draft-touch-tcpm-ao-test-vectors-02 + """ + + master_key = b"testvector" + client_keyid = 61 + server_keyid = 84 + client_ipv4 = IPv4Address("10.11.12.13") + client_ipv6 = IPv6Address("FD00::1") + server_ipv4 = IPv4Address("172.27.28.29") + server_ipv6 = IPv6Address("FD00::2") + + client_isn_41x = 0xFBFBAB5A + server_isn_41x = 0x11C14261 + client_isn_42x = 0xCB0EFBEE + server_isn_42x = 0xACD5B5E1 + client_isn_61x = 0x176A833F + server_isn_61x = 0x3F51994B + client_isn_62x = 0x020C1E69 + server_isn_62x = 0xEBA3734D + + def check( + self, + packet_hex: str, + traffic_key_hex: str, + mac_hex: str, + src_isn, + dst_isn, + include_options=True, + alg_name="HMAC-SHA-1-96", + sne=0, + ): + packet_bytes = bytes.fromhex(packet_hex) + + # sanity check for ip version + ipv = packet_bytes[0] >> 4 + if ipv == 4: + p = IP(bytes.fromhex(packet_hex)) + assert p[IP].proto == socket.IPPROTO_TCP + elif ipv == 6: + p = IPv6(bytes.fromhex(packet_hex)) + assert p[IPv6].nh == socket.IPPROTO_TCP + else: + raise ValueError(f"bad ipv={ipv}") + + # sanity check for seq/ack in SYN/ACK packets + if p[TCP].flags.S and p[TCP].flags.A is False: + assert p[TCP].seq == src_isn + assert p[TCP].ack == 0 + if p[TCP].flags.S and p[TCP].flags.A: + assert p[TCP].seq == src_isn + assert p[TCP].ack == dst_isn + 1 + + # check traffic key + alg = get_alg(alg_name) + context_bytes = build_context_from_packet(p, src_isn, dst_isn) + traffic_key = alg.kdf(self.master_key, context_bytes) + assert traffic_key.hex(" ") == traffic_key_hex + + # check mac + message_bytes = build_message_from_packet( + p, include_options=include_options, sne=sne + ) + mac = alg.mac(traffic_key, message_bytes) + assert mac.hex(" ") == mac_hex + + # check option bytes in header + opt = scapy_tcp_get_authopt_val(p[TCP]) + assert opt is not None + assert opt.keyid in [self.client_keyid, self.server_keyid] + assert opt.rnextkeyid in [self.client_keyid, self.server_keyid] + assert opt.mac.hex(" ") == mac_hex + + def test_4_1_1(self): + self.check( + """ + 45 e0 00 4c dd 0f 40 00 ff 06 bf 6b 0a 0b 0c 0d + ac 1b 1c 1d e9 d7 00 b3 fb fb ab 5a 00 00 00 00 + e0 02 ff ff ca c4 00 00 02 04 05 b4 01 03 03 08 + 04 02 08 0a 00 15 5a b7 00 00 00 00 1d 10 3d 54 + 2e e4 37 c6 f8 ed e6 d7 c4 d6 02 e7 + """, + "6d 63 ef 1b 02 fe 15 09 d4 b1 40 27 07 fd 7b 04 16 ab b7 4f", + "2e e4 37 c6 f8 ed e6 d7 c4 d6 02 e7", + self.client_isn_41x, + 0, + ) + + def test_4_1_2(self): + self.check( + """ + 45 e0 00 4c 65 06 40 00 ff 06 37 75 ac 1b 1c 1d + 0a 0b 0c 0d 00 b3 e9 d7 11 c1 42 61 fb fb ab 5b + e0 12 ff ff 37 76 00 00 02 04 05 b4 01 03 03 08 + 04 02 08 0a 84 a5 0b eb 00 15 5a b7 1d 10 54 3d + ee ab 0f e2 4c 30 10 81 51 16 b3 be + """, + "d9 e2 17 e4 83 4a 80 ca 2f 3f d8 de 2e 41 b8 e6 79 7f ea 96", + "ee ab 0f e2 4c 30 10 81 51 16 b3 be", + self.server_isn_41x, + self.client_isn_41x, + ) + + def test_4_1_3(self): + self.check( + """ + 45 e0 00 87 36 a1 40 00 ff 06 65 9f 0a 0b 0c 0d + ac 1b 1c 1d e9 d7 00 b3 fb fb ab 5b 11 c1 42 62 + c0 18 01 04 a1 62 00 00 01 01 08 0a 00 15 5a c1 + 84 a5 0b eb 1d 10 3d 54 70 64 cf 99 8c c6 c3 15 + c2 c2 e2 bf ff ff ff ff ff ff ff ff ff ff ff ff + ff ff ff ff 00 43 01 04 da bf 00 b4 0a 0b 0c 0d + 26 02 06 01 04 00 01 00 01 02 02 80 00 02 02 02 + 00 02 02 42 00 02 06 41 04 00 00 da bf 02 08 40 + 06 00 64 00 01 01 00 + """, + "d2 e5 9c 65 ff c7 b1 a3 93 47 65 64 63 b7 0e dc 24 a1 3d 71", + "70 64 cf 99 8c c6 c3 15 c2 c2 e2 bf", + self.client_isn_41x, + self.server_isn_41x, + ) + + def test_4_1_4(self): + self.check( + """ + 45 e0 00 87 1f a9 40 00 ff 06 7c 97 ac 1b 1c 1d + 0a 0b 0c 0d 00 b3 e9 d7 11 c1 42 62 fb fb ab 9e + c0 18 01 00 40 0c 00 00 01 01 08 0a 84 a5 0b f5 + 00 15 5a c1 1d 10 54 3d a6 3f 0e cb bb 2e 63 5c + 95 4d ea c7 ff ff ff ff ff ff ff ff ff ff ff ff + ff ff ff ff 00 43 01 04 da c0 00 b4 ac 1b 1c 1d + 26 02 06 01 04 00 01 00 01 02 02 80 00 02 02 02 + 00 02 02 42 00 02 06 41 04 00 00 da c0 02 08 40 + 06 00 64 00 01 01 00 + """, + "d9 e2 17 e4 83 4a 80 ca 2f 3f d8 de 2e 41 b8 e6 79 7f ea 96", + "a6 3f 0e cb bb 2e 63 5c 95 4d ea c7", + self.server_isn_41x, + self.client_isn_41x, + ) + + def test_4_2_1(self): + self.check( + """ + 45 e0 00 4c 53 99 40 00 ff 06 48 e2 0a 0b 0c 0d + ac 1b 1c 1d ff 12 00 b3 cb 0e fb ee 00 00 00 00 + e0 02 ff ff 54 1f 00 00 02 04 05 b4 01 03 03 08 + 04 02 08 0a 00 02 4c ce 00 00 00 00 1d 10 3d 54 + 80 af 3c fe b8 53 68 93 7b 8f 9e c2 + """, + "30 ea a1 56 0c f0 be 57 da b5 c0 45 22 9f b1 0a 42 3c d7 ea", + "80 af 3c fe b8 53 68 93 7b 8f 9e c2", + self.client_isn_42x, + 0, + include_options=False, + ) + + def test_4_2_2(self): + self.check( + """ + 45 e0 00 4c 32 84 40 00 ff 06 69 f7 ac 1b 1c 1d + 0a 0b 0c 0d 00 b3 ff 12 ac d5 b5 e1 cb 0e fb ef + e0 12 ff ff 38 8e 00 00 02 04 05 b4 01 03 03 08 + 04 02 08 0a 57 67 72 f3 00 02 4c ce 1d 10 54 3d + 09 30 6f 9a ce a6 3a 8c 68 cb 9a 70 + """, + "b5 b2 89 6b b3 66 4e 81 76 b0 ed c6 e7 99 52 41 01 a8 30 7f", + "09 30 6f 9a ce a6 3a 8c 68 cb 9a 70", + self.server_isn_42x, + self.client_isn_42x, + include_options=False, + ) + + def test_4_2_3(self): + self.check( + """ + 45 e0 00 87 a8 f5 40 00 ff 06 f3 4a 0a 0b 0c 0d + ac 1b 1c 1d ff 12 00 b3 cb 0e fb ef ac d5 b5 e2 + c0 18 01 04 6c 45 00 00 01 01 08 0a 00 02 4c ce + 57 67 72 f3 1d 10 3d 54 71 06 08 cc 69 6c 03 a2 + 71 c9 3a a5 ff ff ff ff ff ff ff ff ff ff ff ff + ff ff ff ff 00 43 01 04 da bf 00 b4 0a 0b 0c 0d + 26 02 06 01 04 00 01 00 01 02 02 80 00 02 02 02 + 00 02 02 42 00 02 06 41 04 00 00 da bf 02 08 40 + 06 00 64 00 01 01 00 + """, + "f3 db 17 93 d7 91 0e cd 80 6c 34 f1 55 ea 1f 00 34 59 53 e3", + "71 06 08 cc 69 6c 03 a2 71 c9 3a a5", + self.client_isn_42x, + self.server_isn_42x, + include_options=False, + ) + + def test_4_2_4(self): + self.check( + """ + 45 e0 00 87 54 37 40 00 ff 06 48 09 ac 1b 1c 1d + 0a 0b 0c 0d 00 b3 ff 12 ac d5 b5 e2 cb 0e fc 32 + c0 18 01 00 46 b6 00 00 01 01 08 0a 57 67 72 f3 + 00 02 4c ce 1d 10 54 3d 97 76 6e 48 ac 26 2d e9 + ae 61 b4 f9 ff ff ff ff ff ff ff ff ff ff ff ff + ff ff ff ff 00 43 01 04 da c0 00 b4 ac 1b 1c 1d + 26 02 06 01 04 00 01 00 01 02 02 80 00 02 02 02 + 00 02 02 42 00 02 06 41 04 00 00 da c0 02 08 40 + 06 00 64 00 01 01 00 + """, + "b5 b2 89 6b b3 66 4e 81 76 b0 ed c6 e7 99 52 41 01 a8 30 7f", + "97 76 6e 48 ac 26 2d e9 ae 61 b4 f9", + self.server_isn_42x, + self.client_isn_42x, + include_options=False, + ) + + def test_5_1_1(self): + self.check( + """ + 45 e0 00 4c 7b 9f 40 00 ff 06 20 dc 0a 0b 0c 0d + ac 1b 1c 1d c4 fa 00 b3 78 7a 1d df 00 00 00 00 + e0 02 ff ff 5a 0f 00 00 02 04 05 b4 01 03 03 08 + 04 02 08 0a 00 01 7e d0 00 00 00 00 1d 10 3d 54 + e4 77 e9 9c 80 40 76 54 98 e5 50 91 + """, + "f5 b8 b3 d5 f3 4f db b6 eb 8d 4a b9 66 0e 60 e3", + "e4 77 e9 9c 80 40 76 54 98 e5 50 91", + 0x787A1DDF, + 0, + include_options=True, + alg_name="AES-128-CMAC-96", + ) + + def test_6_1_1(self): + self.check( + """ + 6e 08 91 dc 00 38 06 40 fd 00 00 00 00 00 00 00 + 00 00 00 00 00 00 00 01 fd 00 00 00 00 00 00 00 + 00 00 00 00 00 00 00 02 f7 e4 00 b3 17 6a 83 3f + 00 00 00 00 e0 02 ff ff 47 21 00 00 02 04 05 a0 + 01 03 03 08 04 02 08 0a 00 41 d0 87 00 00 00 00 + 1d 10 3d 54 90 33 ec 3d 73 34 b6 4c 5e dd 03 9f + """, + "62 5e c0 9d 57 58 36 ed c9 b6 42 84 18 bb f0 69 89 a3 61 bb", + "90 33 ec 3d 73 34 b6 4c 5e dd 03 9f", + self.client_isn_61x, + 0, + include_options=True, + ) + + def test_6_1_2(self): + self.check( + """ + 6e 01 00 9e 00 38 06 40 fd 00 00 00 00 00 00 00 + 00 00 00 00 00 00 00 02 fd 00 00 00 00 00 00 00 + 00 00 00 00 00 00 00 01 00 b3 f7 e4 3f 51 99 4b + 17 6a 83 40 e0 12 ff ff bf ec 00 00 02 04 05 a0 + 01 03 03 08 04 02 08 0a bd 33 12 9b 00 41 d0 87 + 1d 10 54 3d f1 cb a3 46 c3 52 61 63 f7 1f 1f 55 + """, + "e4 a3 7a da 2a 0a fc a8 71 14 34 91 3f e1 38 c7 71 eb cb 4a", + "f1 cb a3 46 c3 52 61 63 f7 1f 1f 55", + self.server_isn_61x, + self.client_isn_61x, + include_options=True, + ) + + def test_6_2_2(self): + self.check( + """ + 6e 0a 7e 1f 00 38 06 40 fd 00 00 00 00 00 00 00 + 00 00 00 00 00 00 00 02 fd 00 00 00 00 00 00 00 + 00 00 00 00 00 00 00 01 00 b3 c6 cd eb a3 73 4d + 02 0c 1e 6a e0 12 ff ff 77 4d 00 00 02 04 05 a0 + 01 03 03 08 04 02 08 0a 5e c9 9b 70 00 9d b9 5b + 1d 10 54 3d 3c 54 6b ad 97 43 f1 2d f8 b8 01 0d + """, + "40 51 08 94 7f 99 65 75 e7 bd bc 26 d4 02 16 a2 c7 fa 91 bd", + "3c 54 6b ad 97 43 f1 2d f8 b8 01 0d", + self.server_isn_62x, + self.client_isn_62x, + include_options=False, + ) + + def test_6_2_4(self): + self.check( + """ + 6e 0a 7e 1f 00 73 06 40 fd 00 00 00 00 00 00 00 + 00 00 00 00 00 00 00 02 fd 00 00 00 00 00 00 00 + 00 00 00 00 00 00 00 01 00 b3 c6 cd eb a3 73 4e + 02 0c 1e ad c0 18 01 00 71 6a 00 00 01 01 08 0a + 5e c9 9b 7a 00 9d b9 65 1d 10 54 3d 55 9a 81 94 + 45 b4 fd e9 8d 9e 13 17 ff ff ff ff ff ff ff ff + ff ff ff ff ff ff ff ff 00 43 01 04 fd e8 00 b4 + 01 01 01 7a 26 02 06 01 04 00 01 00 01 02 02 80 + 00 02 02 02 00 02 02 42 00 02 06 41 04 00 00 fd + e8 02 08 40 06 00 64 00 01 01 00 + """, + "40 51 08 94 7f 99 65 75 e7 bd bc 26 d4 02 16 a2 c7 fa 91 bd", + "55 9a 81 94 45 b4 fd e9 8d 9e 13 17", + self.server_isn_62x, + self.client_isn_62x, + include_options=False, + ) + + server_isn_71x = 0xA6744ECB + client_isn_71x = 0x193CCCEC + + def test_7_1_2(self): + self.check( + """ + 6e 06 15 20 00 38 06 40 fd 00 00 00 00 00 00 00 + 00 00 00 00 00 00 00 02 fd 00 00 00 00 00 00 00 + 00 00 00 00 00 00 00 01 00 b3 f8 5a a6 74 4e cb + 19 3c cc ed e0 12 ff ff ea bb 00 00 02 04 05 a0 + 01 03 03 08 04 02 08 0a 71 da ab c8 13 e4 ab 99 + 1d 10 54 3d dc 28 43 a8 4e 78 a6 bc fd c5 ed 80 + """, + "cf 1b 1e 22 5e 06 a6 36 16 76 4a 06 7b 46 f4 b1", + "dc 28 43 a8 4e 78 a6 bc fd c5 ed 80", + self.server_isn_71x, + self.client_isn_71x, + alg_name="AES-128-CMAC-96", + include_options=True, + ) + + def test_7_1_4(self): + self.check( + """ + 6e 06 15 20 00 73 06 40 fd 00 00 00 00 00 00 00 + 00 00 00 00 00 00 00 02 fd 00 00 00 00 00 00 00 + 00 00 00 00 00 00 00 01 00 b3 f8 5a a6 74 4e cc + 19 3c cd 30 c0 18 01 00 52 f4 00 00 01 01 08 0a + 71 da ab d3 13 e4 ab a3 1d 10 54 3d c1 06 9b 7d + fd 3d 69 3a 6d f3 f2 89 ff ff ff ff ff ff ff ff + ff ff ff ff ff ff ff ff 00 43 01 04 fd e8 00 b4 + 01 01 01 7a 26 02 06 01 04 00 01 00 01 02 02 80 + 00 02 02 02 00 02 02 42 00 02 06 41 04 00 00 fd + e8 02 08 40 06 00 64 00 01 01 00 + """, + "cf 1b 1e 22 5e 06 a6 36 16 76 4a 06 7b 46 f4 b1", + "c1 06 9b 7d fd 3d 69 3a 6d f3 f2 89", + self.server_isn_71x, + self.client_isn_71x, + alg_name="AES-128-CMAC-96", + include_options=True, + ) diff --git a/tools/testing/selftests/tcp_authopt/tcp_authopt_test/validator.py b/tools/testing/selftests/tcp_authopt/tcp_authopt_test/validator.py new file mode 100644 index 000000000000..295220e3964d --- /dev/null +++ b/tools/testing/selftests/tcp_authopt/tcp_authopt_test/validator.py @@ -0,0 +1,138 @@ +# SPDX-License-Identifier: GPL-2.0 +import logging +import typing +from dataclasses import dataclass + +from scapy.layers.inet import TCP +from scapy.packet import Packet + +from . import scapy_tcp_authopt +from .scapy_conntrack import TCPConnectionTracker, get_packet_tcp_connection_key +from .scapy_utils import scapy_tcp_get_authopt_val + +logger = logging.getLogger(__name__) + + +@dataclass +class TcpAuthValidatorKey: + """Representation of a TCP Authentication Option key for the validator + + The matching rules are independent. + """ + + key: bytes + alg_name: str + include_options: bool = True + keyid: typing.Optional[int] = None + sport: typing.Optional[int] = None + dport: typing.Optional[int] = None + + def match_packet(self, p: Packet) -> bool: + """Determine if this key matches a specific packet""" + if not TCP in p: + return False + authopt = scapy_tcp_get_authopt_val(p[TCP]) + if authopt is None: + return False + if self.keyid is not None and authopt.keyid != self.keyid: + return False + if self.sport is not None and p[TCP].sport != self.sport: + return False + if self.dport is not None and p[TCP].dport != self.dport: + return False + return True + + def get_alg_imp(self): + return scapy_tcp_authopt.get_alg(self.alg_name) + + +class TcpAuthValidator: + """Validate TCP Authentication Option signatures inside a capture + + This can track multiple connections, determine their initial sequence numbers + and verify their signatures independently. + + Keys are provided as a collection of `.TcpAuthValidatorKey` + """ + + keys: typing.List[TcpAuthValidatorKey] + tracker: TCPConnectionTracker + any_incomplete: bool = False + any_unsigned: bool = False + any_fail: bool = False + debug_sne: bool = False + + def __init__(self, keys=None): + self.keys = keys or [] + self.tracker = TCPConnectionTracker() + self.conn_dict = {} + + def get_key_for_packet(self, p): + for k in self.keys: + if k.match_packet(p): + return k + return None + + def handle_packet(self, p: Packet): + if not TCP in p: + return + self.tracker.handle_packet(p) + authopt = scapy_tcp_get_authopt_val(p[TCP]) + if not authopt: + self.any_unsigned = True + logger.debug("skip packet without tcp authopt: %r", p) + return + key = self.get_key_for_packet(p) + if not key: + self.any_unsigned = True + logger.debug("skip packet not matching any known keys: %r", p) + return + tcp_track_key = get_packet_tcp_connection_key(p) + conn = self.tracker.get(tcp_track_key) + + if conn is None: + raise ValueError( + "TCPConnectionTracker.handle_packet should have initialized TCPConnectionInfo" + ) + + if not conn.found_syn: + logger.warning("missing SYN for packet %s", p.summary()) + self.any_incomplete = True + return + if not conn.found_synack and not p[TCP].flags.S: + logger.warning("missing SYNACK for packet %s", p.summary()) + self.any_incomplete = True + return + + alg = key.get_alg_imp() + context_bytes = scapy_tcp_authopt.build_context_from_packet( + p, conn.sisn or 0, conn.disn or 0 + ) + traffic_key = alg.kdf(key.key, context_bytes) + sne = conn.snd_sne.calc(p[TCP].seq, update=False) + if self.debug_sne: + logger.debug("sne %08x seq %08x for %s", sne, p[TCP].seq, p[TCP].summary()) + message_bytes = scapy_tcp_authopt.build_message_from_packet( + p, + include_options=key.include_options, + sne=sne, + ) + computed_mac = alg.mac(traffic_key, message_bytes) + captured_mac = authopt.mac + if computed_mac == captured_mac: + logger.debug("ok - mac %s", computed_mac.hex()) + else: + self.any_fail = True + logger.error( + "not ok - captured %s computed %s", + captured_mac.hex(), + computed_mac.hex(), + ) + + def raise_errors(self, allow_unsigned=False, allow_incomplete=False): + if self.any_fail: + raise Exception("Found failed signatures") + if self.any_incomplete and not allow_incomplete: + raise Exception("Incomplete capture missing SYN/ACK") + if self.any_unsigned and not allow_unsigned: + raise Exception("Found unsigned packets")