/usr/lib/python3/dist-packages/acme/challenges.py is in python3-acme 0.22.2-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 | """ACME Identifier Validation Challenges."""
import abc
import functools
import hashlib
import logging
import socket
from cryptography.hazmat.primitives import hashes # type: ignore
import josepy as jose
import OpenSSL
import requests
from acme import errors
from acme import crypto_util
from acme import fields
logger = logging.getLogger(__name__)
# pylint: disable=too-few-public-methods
class Challenge(jose.TypedJSONObjectWithFields):
# _fields_to_partial_json | pylint: disable=abstract-method
"""ACME challenge."""
TYPES = {} # type: dict
@classmethod
def from_json(cls, jobj):
try:
return super(Challenge, cls).from_json(jobj)
except jose.UnrecognizedTypeError as error:
logger.debug(error)
return UnrecognizedChallenge.from_json(jobj)
class ChallengeResponse(jose.TypedJSONObjectWithFields):
# _fields_to_partial_json | pylint: disable=abstract-method
"""ACME challenge response."""
TYPES = {} # type: dict
resource_type = 'challenge'
resource = fields.Resource(resource_type)
class UnrecognizedChallenge(Challenge):
"""Unrecognized challenge.
ACME specification defines a generic framework for challenges and
defines some standard challenges that are implemented in this
module. However, other implementations (including peers) might
define additional challenge types, which should be ignored if
unrecognized.
:ivar jobj: Original JSON decoded object.
"""
def __init__(self, jobj):
super(UnrecognizedChallenge, self).__init__()
object.__setattr__(self, "jobj", jobj)
def to_partial_json(self):
# pylint: disable=no-member
return self.jobj
@classmethod
def from_json(cls, jobj):
return cls(jobj)
class _TokenChallenge(Challenge):
"""Challenge with token.
:ivar bytes token:
"""
TOKEN_SIZE = 128 / 8 # Based on the entropy value from the spec
"""Minimum size of the :attr:`token` in bytes."""
# TODO: acme-spec doesn't specify token as base64-encoded value
token = jose.Field(
"token", encoder=jose.encode_b64jose, decoder=functools.partial(
jose.decode_b64jose, size=TOKEN_SIZE, minimum=True))
# XXX: rename to ~token_good_for_url
@property
def good_token(self): # XXX: @token.decoder
"""Is `token` good?
.. todo:: acme-spec wants "It MUST NOT contain any non-ASCII
characters", but it should also warrant that it doesn't
contain ".." or "/"...
"""
# TODO: check that path combined with uri does not go above
# URI_ROOT_PATH!
return b'..' not in self.token and b'/' not in self.token
class KeyAuthorizationChallengeResponse(ChallengeResponse):
"""Response to Challenges based on Key Authorization.
:param unicode key_authorization:
"""
key_authorization = jose.Field("keyAuthorization")
thumbprint_hash_function = hashes.SHA256
def verify(self, chall, account_public_key):
"""Verify the key authorization.
:param KeyAuthorization chall: Challenge that corresponds to
this response.
:param JWK account_public_key:
:return: ``True`` iff verification of the key authorization was
successful.
:rtype: bool
"""
parts = self.key_authorization.split('.') # pylint: disable=no-member
if len(parts) != 2:
logger.debug("Key authorization (%r) is not well formed",
self.key_authorization)
return False
if parts[0] != chall.encode("token"):
logger.debug("Mismatching token in key authorization: "
"%r instead of %r", parts[0], chall.encode("token"))
return False
thumbprint = jose.b64encode(account_public_key.thumbprint(
hash_function=self.thumbprint_hash_function)).decode()
if parts[1] != thumbprint:
logger.debug("Mismatching thumbprint in key authorization: "
"%r instead of %r", parts[0], thumbprint)
return False
return True
class KeyAuthorizationChallenge(_TokenChallenge):
# pylint: disable=abstract-class-little-used,too-many-ancestors
"""Challenge based on Key Authorization.
:param response_cls: Subclass of `KeyAuthorizationChallengeResponse`
that will be used to generate `response`.
"""
__metaclass__ = abc.ABCMeta
response_cls = NotImplemented
thumbprint_hash_function = (
KeyAuthorizationChallengeResponse.thumbprint_hash_function)
def key_authorization(self, account_key):
"""Generate Key Authorization.
:param JWK account_key:
:rtype unicode:
"""
return self.encode("token") + "." + jose.b64encode(
account_key.thumbprint(
hash_function=self.thumbprint_hash_function)).decode()
def response(self, account_key):
"""Generate response to the challenge.
:param JWK account_key:
:returns: Response (initialized `response_cls`) to the challenge.
:rtype: KeyAuthorizationChallengeResponse
"""
return self.response_cls(
key_authorization=self.key_authorization(account_key))
@abc.abstractmethod
def validation(self, account_key, **kwargs):
"""Generate validation for the challenge.
Subclasses must implement this method, but they are likely to
return completely different data structures, depending on what's
necessary to complete the challenge. Interpretation of that
return value must be known to the caller.
:param JWK account_key:
:returns: Challenge-specific validation.
"""
raise NotImplementedError() # pragma: no cover
def response_and_validation(self, account_key, *args, **kwargs):
"""Generate response and validation.
Convenience function that return results of `response` and
`validation`.
:param JWK account_key:
:rtype: tuple
"""
return (self.response(account_key),
self.validation(account_key, *args, **kwargs))
@ChallengeResponse.register
class DNS01Response(KeyAuthorizationChallengeResponse):
"""ACME dns-01 challenge response."""
typ = "dns-01"
def simple_verify(self, chall, domain, account_public_key):
"""Simple verify.
This method no longer checks DNS records and is a simple wrapper
around `KeyAuthorizationChallengeResponse.verify`.
:param challenges.DNS01 chall: Corresponding challenge.
:param unicode domain: Domain name being verified.
:param JWK account_public_key: Public key for the key pair
being authorized.
:return: ``True`` iff verification of the key authorization was
successful.
:rtype: bool
"""
# pylint: disable=unused-argument
verified = self.verify(chall, account_public_key)
if not verified:
logger.debug("Verification of key authorization in response failed")
return verified
@Challenge.register # pylint: disable=too-many-ancestors
class DNS01(KeyAuthorizationChallenge):
"""ACME dns-01 challenge."""
response_cls = DNS01Response
typ = response_cls.typ
LABEL = "_acme-challenge"
"""Label clients prepend to the domain name being validated."""
def validation(self, account_key, **unused_kwargs):
"""Generate validation.
:param JWK account_key:
:rtype: unicode
"""
return jose.b64encode(hashlib.sha256(self.key_authorization(
account_key).encode("utf-8")).digest()).decode()
def validation_domain_name(self, name):
"""Domain name for TXT validation record.
:param unicode name: Domain name being validated.
"""
return "{0}.{1}".format(self.LABEL, name)
@ChallengeResponse.register
class HTTP01Response(KeyAuthorizationChallengeResponse):
"""ACME http-01 challenge response."""
typ = "http-01"
PORT = 80
"""Verification port as defined by the protocol.
You can override it (e.g. for testing) by passing ``port`` to
`simple_verify`.
"""
WHITESPACE_CUTSET = "\n\r\t "
"""Whitespace characters which should be ignored at the end of the body."""
def simple_verify(self, chall, domain, account_public_key, port=None):
"""Simple verify.
:param challenges.SimpleHTTP chall: Corresponding challenge.
:param unicode domain: Domain name being verified.
:param JWK account_public_key: Public key for the key pair
being authorized.
:param int port: Port used in the validation.
:returns: ``True`` iff validation with the files currently served by the
HTTP server is successful.
:rtype: bool
"""
if not self.verify(chall, account_public_key):
logger.debug("Verification of key authorization in response failed")
return False
# TODO: ACME specification defines URI template that doesn't
# allow to use a custom port... Make sure port is not in the
# request URI, if it's standard.
if port is not None and port != self.PORT:
logger.warning(
"Using non-standard port for http-01 verification: %s", port)
domain += ":{0}".format(port)
uri = chall.uri(domain)
logger.debug("Verifying %s at %s...", chall.typ, uri)
try:
http_response = requests.get(uri)
except requests.exceptions.RequestException as error:
logger.error("Unable to reach %s: %s", uri, error)
return False
logger.debug("Received %s: %s. Headers: %s", http_response,
http_response.text, http_response.headers)
challenge_response = http_response.text.rstrip(self.WHITESPACE_CUTSET)
if self.key_authorization != challenge_response:
logger.debug("Key authorization from response (%r) doesn't match "
"HTTP response (%r)", self.key_authorization,
challenge_response)
return False
return True
@Challenge.register # pylint: disable=too-many-ancestors
class HTTP01(KeyAuthorizationChallenge):
"""ACME http-01 challenge."""
response_cls = HTTP01Response
typ = response_cls.typ
URI_ROOT_PATH = ".well-known/acme-challenge"
"""URI root path for the server provisioned resource."""
@property
def path(self):
"""Path (starting with '/') for provisioned resource.
:rtype: string
"""
return '/' + self.URI_ROOT_PATH + '/' + self.encode('token')
def uri(self, domain):
"""Create an URI to the provisioned resource.
Forms an URI to the HTTPS server provisioned resource
(containing :attr:`~SimpleHTTP.token`).
:param unicode domain: Domain name being verified.
:rtype: string
"""
return "http://" + domain + self.path
def validation(self, account_key, **unused_kwargs):
"""Generate validation.
:param JWK account_key:
:rtype: unicode
"""
return self.key_authorization(account_key)
@ChallengeResponse.register
class TLSSNI01Response(KeyAuthorizationChallengeResponse):
"""ACME tls-sni-01 challenge response."""
typ = "tls-sni-01"
DOMAIN_SUFFIX = b".acme.invalid"
"""Domain name suffix."""
PORT = 443
"""Verification port as defined by the protocol.
You can override it (e.g. for testing) by passing ``port`` to
`simple_verify`.
"""
@property
def z(self): # pylint: disable=invalid-name
"""``z`` value used for verification.
:rtype bytes:
"""
return hashlib.sha256(
self.key_authorization.encode("utf-8")).hexdigest().lower().encode()
@property
def z_domain(self):
"""Domain name used for verification, generated from `z`.
:rtype bytes:
"""
return self.z[:32] + b'.' + self.z[32:] + self.DOMAIN_SUFFIX
def gen_cert(self, key=None, bits=2048):
"""Generate tls-sni-01 certificate.
:param OpenSSL.crypto.PKey key: Optional private key used in
certificate generation. If not provided (``None``), then
fresh key will be generated.
:param int bits: Number of bits for newly generated key.
:rtype: `tuple` of `OpenSSL.crypto.X509` and `OpenSSL.crypto.PKey`
"""
if key is None:
key = OpenSSL.crypto.PKey()
key.generate_key(OpenSSL.crypto.TYPE_RSA, bits)
return crypto_util.gen_ss_cert(key, [
# z_domain is too big to fit into CN, hence first dummy domain
'dummy', self.z_domain.decode()], force_san=True), key
def probe_cert(self, domain, **kwargs):
"""Probe tls-sni-01 challenge certificate.
:param unicode domain:
"""
# TODO: domain is not necessary if host is provided
if "host" not in kwargs:
host = socket.gethostbyname(domain)
logger.debug('%s resolved to %s', domain, host)
kwargs["host"] = host
kwargs.setdefault("port", self.PORT)
kwargs["name"] = self.z_domain
# TODO: try different methods?
# pylint: disable=protected-access
return crypto_util.probe_sni(**kwargs)
def verify_cert(self, cert):
"""Verify tls-sni-01 challenge certificate.
:param OpensSSL.crypto.X509 cert: Challenge certificate.
:returns: Whether the certificate was successfully verified.
:rtype: bool
"""
# pylint: disable=protected-access
sans = crypto_util._pyopenssl_cert_or_req_san(cert)
logger.debug('Certificate %s. SANs: %s', cert.digest('sha256'), sans)
return self.z_domain.decode() in sans
def simple_verify(self, chall, domain, account_public_key,
cert=None, **kwargs):
"""Simple verify.
Verify ``validation`` using ``account_public_key``, optionally
probe tls-sni-01 certificate and check using `verify_cert`.
:param .challenges.TLSSNI01 chall: Corresponding challenge.
:param str domain: Domain name being validated.
:param JWK account_public_key:
:param OpenSSL.crypto.X509 cert: Optional certificate. If not
provided (``None``) certificate will be retrieved using
`probe_cert`.
:param int port: Port used to probe the certificate.
:returns: ``True`` iff client's control of the domain has been
verified.
:rtype: bool
"""
if not self.verify(chall, account_public_key):
logger.debug("Verification of key authorization in response failed")
return False
if cert is None:
try:
cert = self.probe_cert(domain=domain, **kwargs)
except errors.Error as error:
logger.debug(error, exc_info=True)
return False
return self.verify_cert(cert)
@Challenge.register # pylint: disable=too-many-ancestors
class TLSSNI01(KeyAuthorizationChallenge):
"""ACME tls-sni-01 challenge."""
response_cls = TLSSNI01Response
typ = response_cls.typ
# boulder#962, ietf-wg-acme#22
#n = jose.Field("n", encoder=int, decoder=int)
def validation(self, account_key, **kwargs):
"""Generate validation.
:param JWK account_key:
:param OpenSSL.crypto.PKey cert_key: Optional private key used
in certificate generation. If not provided (``None``), then
fresh key will be generated.
:rtype: `tuple` of `OpenSSL.crypto.X509` and `OpenSSL.crypto.PKey`
"""
return self.response(account_key).gen_cert(key=kwargs.get('cert_key'))
@Challenge.register # pylint: disable=too-many-ancestors
class DNS(_TokenChallenge):
"""ACME "dns" challenge."""
typ = "dns"
LABEL = "_acme-challenge"
"""Label clients prepend to the domain name being validated."""
def gen_validation(self, account_key, alg=jose.RS256, **kwargs):
"""Generate validation.
:param .JWK account_key: Private account key.
:param .JWA alg:
:returns: This challenge wrapped in `.JWS`
:rtype: .JWS
"""
return jose.JWS.sign(
payload=self.json_dumps(sort_keys=True).encode('utf-8'),
key=account_key, alg=alg, **kwargs)
def check_validation(self, validation, account_public_key):
"""Check validation.
:param JWS validation:
:param JWK account_public_key:
:rtype: bool
"""
if not validation.verify(key=account_public_key):
return False
try:
return self == self.json_loads(
validation.payload.decode('utf-8'))
except jose.DeserializationError as error:
logger.debug("Checking validation for DNS failed: %s", error)
return False
def gen_response(self, account_key, **kwargs):
"""Generate response.
:param .JWK account_key: Private account key.
:param .JWA alg:
:rtype: DNSResponse
"""
return DNSResponse(validation=self.gen_validation(
account_key, **kwargs))
def validation_domain_name(self, name):
"""Domain name for TXT validation record.
:param unicode name: Domain name being validated.
"""
return "{0}.{1}".format(self.LABEL, name)
@ChallengeResponse.register
class DNSResponse(ChallengeResponse):
"""ACME "dns" challenge response.
:param JWS validation:
"""
typ = "dns"
validation = jose.Field("validation", decoder=jose.JWS.from_json)
def check_validation(self, chall, account_public_key):
"""Check validation.
:param challenges.DNS chall:
:param JWK account_public_key:
:rtype: bool
"""
return chall.check_validation(self.validation, account_public_key)
|