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Diffstat (limited to '.venv/lib/python3.12/site-packages/dns/tsig.py')
-rw-r--r-- | .venv/lib/python3.12/site-packages/dns/tsig.py | 352 |
1 files changed, 352 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/dns/tsig.py b/.venv/lib/python3.12/site-packages/dns/tsig.py new file mode 100644 index 00000000..780852e8 --- /dev/null +++ b/.venv/lib/python3.12/site-packages/dns/tsig.py @@ -0,0 +1,352 @@ +# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license + +# Copyright (C) 2001-2007, 2009-2011 Nominum, Inc. +# +# Permission to use, copy, modify, and distribute this software and its +# documentation for any purpose with or without fee is hereby granted, +# provided that the above copyright notice and this permission notice +# appear in all copies. +# +# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES +# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF +# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR +# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES +# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN +# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT +# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + +"""DNS TSIG support.""" + +import base64 +import hashlib +import hmac +import struct + +import dns.exception +import dns.name +import dns.rcode +import dns.rdataclass + + +class BadTime(dns.exception.DNSException): + """The current time is not within the TSIG's validity time.""" + + +class BadSignature(dns.exception.DNSException): + """The TSIG signature fails to verify.""" + + +class BadKey(dns.exception.DNSException): + """The TSIG record owner name does not match the key.""" + + +class BadAlgorithm(dns.exception.DNSException): + """The TSIG algorithm does not match the key.""" + + +class PeerError(dns.exception.DNSException): + """Base class for all TSIG errors generated by the remote peer""" + + +class PeerBadKey(PeerError): + """The peer didn't know the key we used""" + + +class PeerBadSignature(PeerError): + """The peer didn't like the signature we sent""" + + +class PeerBadTime(PeerError): + """The peer didn't like the time we sent""" + + +class PeerBadTruncation(PeerError): + """The peer didn't like amount of truncation in the TSIG we sent""" + + +# TSIG Algorithms + +HMAC_MD5 = dns.name.from_text("HMAC-MD5.SIG-ALG.REG.INT") +HMAC_SHA1 = dns.name.from_text("hmac-sha1") +HMAC_SHA224 = dns.name.from_text("hmac-sha224") +HMAC_SHA256 = dns.name.from_text("hmac-sha256") +HMAC_SHA256_128 = dns.name.from_text("hmac-sha256-128") +HMAC_SHA384 = dns.name.from_text("hmac-sha384") +HMAC_SHA384_192 = dns.name.from_text("hmac-sha384-192") +HMAC_SHA512 = dns.name.from_text("hmac-sha512") +HMAC_SHA512_256 = dns.name.from_text("hmac-sha512-256") +GSS_TSIG = dns.name.from_text("gss-tsig") + +default_algorithm = HMAC_SHA256 + +mac_sizes = { + HMAC_SHA1: 20, + HMAC_SHA224: 28, + HMAC_SHA256: 32, + HMAC_SHA256_128: 16, + HMAC_SHA384: 48, + HMAC_SHA384_192: 24, + HMAC_SHA512: 64, + HMAC_SHA512_256: 32, + HMAC_MD5: 16, + GSS_TSIG: 128, # This is what we assume to be the worst case! +} + + +class GSSTSig: + """ + GSS-TSIG TSIG implementation. This uses the GSS-API context established + in the TKEY message handshake to sign messages using GSS-API message + integrity codes, per the RFC. + + In order to avoid a direct GSSAPI dependency, the keyring holds a ref + to the GSSAPI object required, rather than the key itself. + """ + + def __init__(self, gssapi_context): + self.gssapi_context = gssapi_context + self.data = b"" + self.name = "gss-tsig" + + def update(self, data): + self.data += data + + def sign(self): + # defer to the GSSAPI function to sign + return self.gssapi_context.get_signature(self.data) + + def verify(self, expected): + try: + # defer to the GSSAPI function to verify + return self.gssapi_context.verify_signature(self.data, expected) + except Exception: + # note the usage of a bare exception + raise BadSignature + + +class GSSTSigAdapter: + def __init__(self, keyring): + self.keyring = keyring + + def __call__(self, message, keyname): + if keyname in self.keyring: + key = self.keyring[keyname] + if isinstance(key, Key) and key.algorithm == GSS_TSIG: + if message: + GSSTSigAdapter.parse_tkey_and_step(key, message, keyname) + return key + else: + return None + + @classmethod + def parse_tkey_and_step(cls, key, message, keyname): + # if the message is a TKEY type, absorb the key material + # into the context using step(); this is used to allow the + # client to complete the GSSAPI negotiation before attempting + # to verify the signed response to a TKEY message exchange + try: + rrset = message.find_rrset( + message.answer, keyname, dns.rdataclass.ANY, dns.rdatatype.TKEY + ) + if rrset: + token = rrset[0].key + gssapi_context = key.secret + return gssapi_context.step(token) + except KeyError: + pass + + +class HMACTSig: + """ + HMAC TSIG implementation. This uses the HMAC python module to handle the + sign/verify operations. + """ + + _hashes = { + HMAC_SHA1: hashlib.sha1, + HMAC_SHA224: hashlib.sha224, + HMAC_SHA256: hashlib.sha256, + HMAC_SHA256_128: (hashlib.sha256, 128), + HMAC_SHA384: hashlib.sha384, + HMAC_SHA384_192: (hashlib.sha384, 192), + HMAC_SHA512: hashlib.sha512, + HMAC_SHA512_256: (hashlib.sha512, 256), + HMAC_MD5: hashlib.md5, + } + + def __init__(self, key, algorithm): + try: + hashinfo = self._hashes[algorithm] + except KeyError: + raise NotImplementedError(f"TSIG algorithm {algorithm} is not supported") + + # create the HMAC context + if isinstance(hashinfo, tuple): + self.hmac_context = hmac.new(key, digestmod=hashinfo[0]) + self.size = hashinfo[1] + else: + self.hmac_context = hmac.new(key, digestmod=hashinfo) + self.size = None + self.name = self.hmac_context.name + if self.size: + self.name += f"-{self.size}" + + def update(self, data): + return self.hmac_context.update(data) + + def sign(self): + # defer to the HMAC digest() function for that digestmod + digest = self.hmac_context.digest() + if self.size: + digest = digest[: (self.size // 8)] + return digest + + def verify(self, expected): + # re-digest and compare the results + mac = self.sign() + if not hmac.compare_digest(mac, expected): + raise BadSignature + + +def _digest(wire, key, rdata, time=None, request_mac=None, ctx=None, multi=None): + """Return a context containing the TSIG rdata for the input parameters + @rtype: dns.tsig.HMACTSig or dns.tsig.GSSTSig object + @raises ValueError: I{other_data} is too long + @raises NotImplementedError: I{algorithm} is not supported + """ + + first = not (ctx and multi) + if first: + ctx = get_context(key) + if request_mac: + ctx.update(struct.pack("!H", len(request_mac))) + ctx.update(request_mac) + ctx.update(struct.pack("!H", rdata.original_id)) + ctx.update(wire[2:]) + if first: + ctx.update(key.name.to_digestable()) + ctx.update(struct.pack("!H", dns.rdataclass.ANY)) + ctx.update(struct.pack("!I", 0)) + if time is None: + time = rdata.time_signed + upper_time = (time >> 32) & 0xFFFF + lower_time = time & 0xFFFFFFFF + time_encoded = struct.pack("!HIH", upper_time, lower_time, rdata.fudge) + other_len = len(rdata.other) + if other_len > 65535: + raise ValueError("TSIG Other Data is > 65535 bytes") + if first: + ctx.update(key.algorithm.to_digestable() + time_encoded) + ctx.update(struct.pack("!HH", rdata.error, other_len) + rdata.other) + else: + ctx.update(time_encoded) + return ctx + + +def _maybe_start_digest(key, mac, multi): + """If this is the first message in a multi-message sequence, + start a new context. + @rtype: dns.tsig.HMACTSig or dns.tsig.GSSTSig object + """ + if multi: + ctx = get_context(key) + ctx.update(struct.pack("!H", len(mac))) + ctx.update(mac) + return ctx + else: + return None + + +def sign(wire, key, rdata, time=None, request_mac=None, ctx=None, multi=False): + """Return a (tsig_rdata, mac, ctx) tuple containing the HMAC TSIG rdata + for the input parameters, the HMAC MAC calculated by applying the + TSIG signature algorithm, and the TSIG digest context. + @rtype: (string, dns.tsig.HMACTSig or dns.tsig.GSSTSig object) + @raises ValueError: I{other_data} is too long + @raises NotImplementedError: I{algorithm} is not supported + """ + + ctx = _digest(wire, key, rdata, time, request_mac, ctx, multi) + mac = ctx.sign() + tsig = rdata.replace(time_signed=time, mac=mac) + + return (tsig, _maybe_start_digest(key, mac, multi)) + + +def validate( + wire, key, owner, rdata, now, request_mac, tsig_start, ctx=None, multi=False +): + """Validate the specified TSIG rdata against the other input parameters. + + @raises FormError: The TSIG is badly formed. + @raises BadTime: There is too much time skew between the client and the + server. + @raises BadSignature: The TSIG signature did not validate + @rtype: dns.tsig.HMACTSig or dns.tsig.GSSTSig object""" + + (adcount,) = struct.unpack("!H", wire[10:12]) + if adcount == 0: + raise dns.exception.FormError + adcount -= 1 + new_wire = wire[0:10] + struct.pack("!H", adcount) + wire[12:tsig_start] + if rdata.error != 0: + if rdata.error == dns.rcode.BADSIG: + raise PeerBadSignature + elif rdata.error == dns.rcode.BADKEY: + raise PeerBadKey + elif rdata.error == dns.rcode.BADTIME: + raise PeerBadTime + elif rdata.error == dns.rcode.BADTRUNC: + raise PeerBadTruncation + else: + raise PeerError("unknown TSIG error code %d" % rdata.error) + if abs(rdata.time_signed - now) > rdata.fudge: + raise BadTime + if key.name != owner: + raise BadKey + if key.algorithm != rdata.algorithm: + raise BadAlgorithm + ctx = _digest(new_wire, key, rdata, None, request_mac, ctx, multi) + ctx.verify(rdata.mac) + return _maybe_start_digest(key, rdata.mac, multi) + + +def get_context(key): + """Returns an HMAC context for the specified key. + + @rtype: HMAC context + @raises NotImplementedError: I{algorithm} is not supported + """ + + if key.algorithm == GSS_TSIG: + return GSSTSig(key.secret) + else: + return HMACTSig(key.secret, key.algorithm) + + +class Key: + def __init__(self, name, secret, algorithm=default_algorithm): + if isinstance(name, str): + name = dns.name.from_text(name) + self.name = name + if isinstance(secret, str): + secret = base64.decodebytes(secret.encode()) + self.secret = secret + if isinstance(algorithm, str): + algorithm = dns.name.from_text(algorithm) + self.algorithm = algorithm + + def __eq__(self, other): + return ( + isinstance(other, Key) + and self.name == other.name + and self.secret == other.secret + and self.algorithm == other.algorithm + ) + + def __repr__(self): + r = f"<DNS key name='{self.name}', " + f"algorithm='{self.algorithm}'" + if self.algorithm != GSS_TSIG: + r += f", secret='{base64.b64encode(self.secret).decode()}'" + r += ">" + return r |