class PasswordType(types.TypeDecorator, ScalarCoercible):
"""
PasswordType hashes passwords as they come into the database and allows
verifying them using a pythonic interface.
All keyword arguments (aside from max_length) are forwarded to the
construction of a `passlib.context.CryptContext` object.
The following usage will create a password column that will
automatically hash new passwords as `pbkdf2_sha512` but still compare
passwords against pre-existing `md5_crypt` hashes. As passwords are
compared; the password hash in the database will be updated to
be `pbkdf2_sha512`.
::
class Model(Base):
password = sa.Column(PasswordType(
schemes=[
'pbkdf2_sha512',
'md5_crypt'
],
deprecated=['md5_crypt']
))
Verifying password is as easy as:
::
target = Model()
target.password = '******'
# '$5$rounds=80000$H.............'
target.password == 'b'
# True
"""
impl = types.VARBINARY(1024)
python_type = Password
def __init__(self, max_length=None, **kwargs):
# Fail if passlib is not found.
if passlib is None:
raise ImproperlyConfigured(
"'passlib' is required to use 'PasswordType'")
# Construct the passlib crypt context.
self.context = CryptContext(**kwargs)
if max_length is None:
max_length = self.calculate_max_length()
# Set the length to the now-calculated max length.
self.length = max_length
def calculate_max_length(self):
# Calculate the largest possible encoded password.
# name + rounds + salt + hash + ($ * 4) of largest hash
max_lengths = [1024]
for name in self.context.schemes():
scheme = getattr(__import__('passlib.hash').hash, name)
length = 4 + len(scheme.name)
length += len(str(getattr(scheme, 'max_rounds', '')))
length += (getattr(scheme, 'max_salt_size', 0) or 0)
length += getattr(scheme, 'encoded_checksum_size',
scheme.checksum_size)
max_lengths.append(length)
# Return the maximum calculated max length.
return max(max_lengths)
def load_dialect_impl(self, dialect):
if dialect.name == 'postgresql':
# Use a BYTEA type for postgresql.
impl = postgresql.BYTEA(self.length)
return dialect.type_descriptor(impl)
if dialect.name == 'oracle':
# Use a RAW type for oracle.
impl = oracle.RAW(self.length)
return dialect.type_descriptor(impl)
# Use a VARBINARY for all other dialects.
impl = types.VARBINARY(self.length)
return dialect.type_descriptor(impl)
def process_bind_param(self, value, dialect):
if isinstance(value, Password):
# If were given a password secret; encrypt it.
if value.secret is not None:
return self.context.encrypt(value.secret).encode('utf8')
# Value has already been hashed.
return value.hash
if isinstance(value, six.string_types):
# Assume value has not been hashed.
return self.context.encrypt(value).encode('utf8')
def process_result_value(self, value, dialect):
if value is not None:
return Password(value, self.context)
def _coerce(self, value):
if value is None:
return
if not isinstance(value, Password):
# Hash the password using the default scheme.
value = self.context.encrypt(value).encode('utf8')
return Password(value, context=self.context)
else:
# If were given a password object; ensure the context is right.
value.context = weakref.proxy(self.context)
# If were given a password secret; encrypt it.
if value.secret is not None:
value.hash = self.context.encrypt(value.secret).encode('utf8')
value.secret = None
return value
@property
def python_type(self):
return self.impl.type.python_type
class PasswordType(types.TypeDecorator, ScalarCoercible):
"""
PasswordType hashes passwords as they come into the database and allows
verifying them using a pythonic interface.
All keyword arguments (aside from max_length) are forwarded to the
construction of a `passlib.context.CryptContext` object.
The following usage will create a password column that will
automatically hash new passwords as `pbkdf2_sha512` but still compare
passwords against pre-existing `md5_crypt` hashes. As passwords are
compared; the password hash in the database will be updated to
be `pbkdf2_sha512`.
::
class Model(Base):
password = sa.Column(PasswordType(
schemes=[
'pbkdf2_sha512',
'md5_crypt'
],
deprecated=['md5_crypt']
))
Verifying password is as easy as:
::
target = Model()
target.password = '******'
# '$5$rounds=80000$H.............'
target.password == 'b'
# True
"""
impl = types.VARBINARY(1024)
python_type = Password
def __init__(self, max_length=None, **kwargs):
# Fail if passlib is not found.
if passlib is None:
raise ImproperlyConfigured(
"'passlib' is required to use 'PasswordType'"
)
# Construct the passlib crypt context.
self.context = CryptContext(**kwargs)
if max_length is None:
max_length = self.calculate_max_length()
# Set the length to the now-calculated max length.
self.length = max_length
def calculate_max_length(self):
# Calculate the largest possible encoded password.
# name + rounds + salt + hash + ($ * 4) of largest hash
max_lengths = [1024]
for name in self.context.schemes():
scheme = getattr(__import__('passlib.hash').hash, name)
length = 4 + len(scheme.name)
length += len(str(getattr(scheme, 'max_rounds', '')))
length += (getattr(scheme, 'max_salt_size', 0) or 0)
length += getattr(
scheme,
'encoded_checksum_size',
scheme.checksum_size
)
max_lengths.append(length)
# Return the maximum calculated max length.
return max(max_lengths)
def load_dialect_impl(self, dialect):
if dialect.name == 'postgresql':
# Use a BYTEA type for postgresql.
impl = postgresql.BYTEA(self.length)
return dialect.type_descriptor(impl)
if dialect.name == 'oracle':
# Use a RAW type for oracle.
impl = oracle.RAW(self.length)
return dialect.type_descriptor(impl)
# Use a VARBINARY for all other dialects.
impl = types.VARBINARY(self.length)
return dialect.type_descriptor(impl)
def process_bind_param(self, value, dialect):
if isinstance(value, Password):
# If were given a password secret; encrypt it.
if value.secret is not None:
return self.context.encrypt(value.secret).encode('utf8')
# Value has already been hashed.
return value.hash
if isinstance(value, six.string_types):
# Assume value has not been hashed.
return self.context.encrypt(value).encode('utf8')
def process_result_value(self, value, dialect):
if value is not None:
return Password(value, self.context)
def _coerce(self, value):
if value is None:
return
if not isinstance(value, Password):
# Hash the password using the default scheme.
value = self.context.encrypt(value).encode('utf8')
return Password(value, context=self.context)
else:
# If were given a password object; ensure the context is right.
value.context = weakref.proxy(self.context)
# If were given a password secret; encrypt it.
if value.secret is not None:
value.hash = self.context.encrypt(value.secret).encode('utf8')
value.secret = None
return value
class Praetorian:
"""
Comprises the implementation for the flask-praetorian flask extension.
Provides a tool that allows password authentication and token provision
for applications and designated endpoints
"""
def __init__(
self,
app=None,
user_class=None,
token_store_class=None,
is_blacklisted=None,
encode_jwt_token_hook=None,
refresh_jwt_token_hook=None,
):
self.pwd_ctx = None
self.hash_scheme = None
self.salt = None
# TODO allow there to be only tokens if we want - not that important for now
if app is not None and user_class is not None:
self.init_app(
app,
user_class,
token_store_class,
is_blacklisted,
encode_jwt_token_hook,
refresh_jwt_token_hook,
)
def init_app(
self,
app=None,
user_class=None,
token_store_class=None,
is_blacklisted=None,
encode_jwt_token_hook=None,
refresh_jwt_token_hook=None,
):
"""
Initializes the Praetorian extension
:param: app: The flask app to bind this
extension to
:param: user_class: The class used to interact with
user data
:param: token_store_class: The class used to interact with
token store data
:param: is_blacklisted: A method that may optionally be
used to check the token against
a blacklist when access or refresh
is requested should take the jti
for the token to check as a single
argument. Returns True if the jti is
blacklisted, False otherwise. By
default, always returns False.
:param encode_jwt_token_hook: A method that may optionally be
called right before an encoded jwt
is generated. Should take
payload_parts which contains the
ingredients for the jwt.
:param refresh_jwt_token_hook: A method that may optionally be called
right before an encoded jwt is
refreshed. Should take payload_parts
which contains the ingredients for
the jwt.
"""
PraetorianError.require_condition(
app.config.get('SECRET_KEY') is not None,
"There must be a SECRET_KEY app config setting set",
)
self.roles_disabled = app.config.get(
'PRAETORIAN_ROLES_DISABLED',
DEFAULT_ROLES_DISABLED,
)
self.hash_autoupdate = app.config.get(
'PRAETORIAN_HASH_AUTOUPDATE',
DEFAULT_HASH_AUTOUPDATE,
)
self.hash_autotest = app.config.get(
'PRAETORIAN_HASH_AUTOTEST',
DEFAULT_HASH_AUTOTEST,
)
self.pwd_ctx = CryptContext(
schemes=app.config.get(
'PRAETORIAN_HASH_ALLOWED_SCHEMES',
DEFAULT_HASH_ALLOWED_SCHEMES,
),
default=app.config.get(
'PRAETORIAN_HASH_SCHEME',
DEFAULT_HASH_SCHEME,
),
deprecated=app.config.get(
'PRAETORIAN_HASH_DEPRECATED_SCHEMES',
DEFAULT_HASH_DEPRECATED_SCHEMES,
),
)
valid_schemes = self.pwd_ctx.schemes()
PraetorianError.require_condition(
self.hash_scheme in valid_schemes or self.hash_scheme is None,
"If {} is set, it must be one of the following schemes: {}".format(
'PRAETORIAN_HASH_SCHEME',
valid_schemes,
),
)
self.user_class = self._validate_user_class(user_class)
#self.token_class = self._validate_token_class(token_class)
self.token_store_class = token_store_class
self.is_blacklisted = is_blacklisted or (lambda t: False)
self.encode_jwt_token_hook = encode_jwt_token_hook
self.refresh_jwt_token_hook = refresh_jwt_token_hook
self.encode_key = app.config['SECRET_KEY']
self.allowed_algorithms = app.config.get(
'JWT_ALLOWED_ALGORITHMS',
DEFAULT_JWT_ALLOWED_ALGORITHMS,
)
self.encode_algorithm = app.config.get(
'JWT_ALGORITHM',
DEFAULT_JWT_ALGORITHM,
)
self.access_lifespan = app.config.get(
'JWT_ACCESS_LIFESPAN',
DEFAULT_JWT_ACCESS_LIFESPAN,
)
self.refresh_lifespan = app.config.get(
'JWT_REFRESH_LIFESPAN',
DEFAULT_JWT_REFRESH_LIFESPAN,
)
self.reset_lifespan = app.config.get(
'JWT_RESET_LIFESPAN',
DEFAULT_JWT_RESET_LIFESPAN,
)
self.jwt_places = app.config.get(
'JWT_PLACES',
DEFAULT_JWT_PLACES,
)
self.cookie_name = app.config.get(
'JWT_COOKIE_NAME',
DEFAULT_JWT_COOKIE_NAME,
)
self.header_name = app.config.get(
'JWT_HEADER_NAME',
DEFAULT_JWT_HEADER_NAME,
)
self.header_type = app.config.get(
'JWT_HEADER_TYPE',
DEFAULT_JWT_HEADER_TYPE,
)
self.user_class_validation_method = app.config.get(
'USER_CLASS_VALIDATION_METHOD',
DEFAULT_USER_CLASS_VALIDATION_METHOD,
)
self.confirmation_template = app.config.get(
'PRAETORIAN_CONFIRMATION_TEMPLATE',
DEFAULT_CONFIRMATION_TEMPLATE,
)
self.confirmation_uri = app.config.get('PRAETORIAN_CONFIRMATION_URI', )
self.confirmation_sender = app.config.get(
'PRAETORIAN_CONFIRMATION_SENDER', )
self.confirmation_subject = app.config.get(
'PRAETORIAN_CONFIRMATION_SUBJECT',
DEFAULT_CONFIRMATION_SUBJECT,
)
self.reset_template = app.config.get(
'PRAETORIAN_RESET_TEMPLATE',
DEFAULT_RESET_TEMPLATE,
)
self.reset_uri = app.config.get('PRAETORIAN_RESET_URI', )
self.reset_sender = app.config.get('PRAETORIAN_RESET_SENDER', )
self.reset_subject = app.config.get(
'PRAETORIAN_RESET_SUBJECT',
DEFAULT_RESET_SUBJECT,
)
if isinstance(self.access_lifespan, dict):
self.access_lifespan = pendulum.duration(**self.access_lifespan)
elif isinstance(self.access_lifespan, str):
self.access_lifespan = duration_from_string(self.access_lifespan)
ConfigurationError.require_condition(
isinstance(self.access_lifespan, datetime.timedelta),
"access lifespan was not configured",
)
if isinstance(self.refresh_lifespan, dict):
self.refresh_lifespan = pendulum.duration(**self.refresh_lifespan)
if isinstance(self.refresh_lifespan, str):
self.refresh_lifespan = duration_from_string(self.refresh_lifespan)
ConfigurationError.require_condition(
isinstance(self.refresh_lifespan, datetime.timedelta),
"refresh lifespan was not configured",
)
if not app.config.get('DISABLE_PRAETORIAN_ERROR_HANDLER'):
app.register_error_handler(
PraetorianError,
PraetorianError.build_error_handler(),
)
self.is_testing = app.config.get('TESTING', False)
if not hasattr(app, 'extensions'):
app.extensions = {}
app.extensions['praetorian'] = self
return app
def _validate_user_class(self, user_class):
"""
Validates the supplied user_class to make sure that it has the
class methods and attributes necessary to function correctly.
After validating class methods, will attempt to instantiate a dummy
instance of the user class to test for the requisite attributes
Requirements:
- ``lookup`` method. Accepts a string parameter, returns instance
- ``identify`` method. Accepts an identity parameter, returns instance
- ``identity`` attribute. Provides unique id for the instance
- ``rolenames`` attribute. Provides list of roles attached to instance
- ``password`` attribute. Provides hashed password for instance
"""
PraetorianError.require_condition(
getattr(user_class, 'lookup', None) is not None,
textwrap.dedent("""
The user_class must have a lookup class method:
user_class.lookup(<str>) -> <user instance>
"""),
)
PraetorianError.require_condition(
getattr(user_class, 'identify', None) is not None,
textwrap.dedent("""
The user_class must have an identify class method:
user_class.identify(<identity>) -> <user instance>
"""),
)
dummy_user = None
try:
dummy_user = user_class()
except Exception:
flask.current_app.logger.debug(
"Skipping instance validation because "
"user cannot be instantiated without arguments")
if dummy_user:
PraetorianError.require_condition(
hasattr(dummy_user, "identity"),
textwrap.dedent("""
Instances of user_class must have an identity attribute:
user_instance.identity -> <unique id for instance>
"""),
)
PraetorianError.require_condition(
self.roles_disabled or hasattr(dummy_user, "rolenames"),
textwrap.dedent("""
Instances of user_class must have a rolenames attribute:
user_instance.rolenames -> [<role1>, <role2>, ...]
"""),
)
PraetorianError.require_condition(
hasattr(dummy_user, "password"),
textwrap.dedent("""
Instances of user_class must have a password attribute:
user_instance.rolenames -> <hashed password>
"""),
)
return user_class
def _validate_token_class(self, token_store_class):
"""
Validates the supplied user_class to make sure that it has the
class methods and attributes necessary to function correctly.
After validating class methods, will attempt to instantiate a dummy
instance of the user class to test for the requisite attributes
Requirements:
- ``lookup`` method. Accepts a string parameter, returns instance
- ``identify`` method. Accepts an identity parameter, returns instance
- ``identity`` attribute. Provides unique id for the instance
- ``rolenames`` attribute. Provides list of roles attached to instance
- ``password`` attribute. Provides hashed password for instance # TODO remove password
"""
PraetorianError.require_condition(
getattr(token_store_class, 'lookup', None) is not None,
textwrap.dedent("""
The user_class must have a lookup class method:
user_class.lookup(<str>) -> <user instance>
"""),
)
PraetorianError.require_condition(
getattr(token_store_class, 'identify', None) is not None,
textwrap.dedent("""
The user_class must have an identify class method:
user_class.identify(<identity>) -> <user instance>
"""),
)
dummy_token_store = None
try:
dummy_token_store = token_store_class()
except Exception:
flask.current_app.logger.debug(
"Skipping instance validation because "
"token cannot be instantiated without arguments")
if dummy_token_store:
PraetorianError.require_condition(
hasattr(dummy_token_store, "identity"),
textwrap.dedent("""
Instances of token_class must have an identity attribute:
token_instance.identity -> <unique id for instance>
"""),
)
PraetorianError.require_condition(
self.roles_disabled or hasattr(dummy_token_store, "rolenames"),
textwrap.dedent("""
Instances of token_class must have a rolenames attribute:
token_instance.rolenames -> [<role1>, <role2>, ...]
"""),
)
# PraetorianError.require_condition(
# hasattr(dummy_token, "password"),
# textwrap.dedent("""
# Instances of user_class must have a password attribute:
# user_instance.rolenames -> <hashed password>
# """),
# )
return dummy_token_store
def authenticate(self, username, password):
"""
Verifies that a password matches the stored password for that username.
If verification passes, the matching user instance is returned
"""
PraetorianError.require_condition(
self.user_class is not None,
"Praetorian must be initialized before this method is available",
)
user = self.user_class.lookup(username)
AuthenticationError.require_condition(
user is not None and self._verify_password(
password,
user.password,
),
'The username and/or password are incorrect',
)
"""
If we are set to PRAETORIAN_HASH_AUTOUPDATE then check our hash
and if needed, update the user. The developer is responsible
for using the returned user object and updating the data
storage endpoint.
Else, if we are set to PRAETORIAN_HASH_AUTOTEST then check out hash
and return exception if our hash is using the wrong scheme,
but don't modify the user.
"""
if self.hash_autoupdate:
self.verify_and_update(user=user, password=password)
elif self.hash_autotest:
self.verify_and_update(user=user)
return user
def _verify_password(self, raw_password, hashed_password):
"""
Verifies that a plaintext password matches the hashed version of that
password using the stored passlib password context
"""
PraetorianError.require_condition(
self.pwd_ctx is not None,
"Praetorian must be initialized before this method is available",
)
return self.pwd_ctx.verify(raw_password, hashed_password)
@deprecated('Use `hash_password` instead.')
def encrypt_password(self, raw_password):
"""
*NOTE* This should be deprecated as its an incorrect definition for
what is actually being done -- we are hashing, not encrypting
"""
return self.hash_password(raw_password)
def error_handler(self, error):
"""
Provides a flask error handler that is used for PraetorianErrors
(and derived exceptions).
"""
warnings.warn(
"""
error_handler is deprecated.
Use FlaskBuzz.build_error_handler instead
""",
warnings.DeprecationWarning,
)
return error.jsonify(), error.status_code, error.headers
def _check_user(self, user):
"""
Checks to make sure that a user is valid. First, checks that the user
is not None. If this check fails, a MissingUserError is raised. Next,
checks if the user has a validation method. If the method does not
exist, the check passes. If the method exists, it is called. If the
result of the call is not truthy, an InvalidUserError is raised
"""
MissingUserError.require_condition(
user is not None,
'Could not find the requested user',
)
user_validate_method = getattr(user, self.user_class_validation_method,
None)
if user_validate_method is None:
return
InvalidUserError.require_condition(
user_validate_method(),
"The user is not valid or has had access revoked",
)
def encode_jwt_token(self,
user,
override_access_lifespan=None,
override_refresh_lifespan=None,
bypass_user_check=False,
is_registration_token=False,
is_reset_token=False,
**custom_claims):
"""
Encodes user data into a jwt token that can be used for authorization
at protected endpoints
:param: override_access_lifespan: Override's the instance's access
lifespan to set a custom duration
after which the new token's
accessability will expire. May not
exceed the refresh_lifespan
:param: override_refresh_lifespan: Override's the instance's refresh
lifespan to set a custom duration
after which the new token's
refreshability will expire.
:param: bypass_user_check: Override checking the user for
being real/active. Used for
registration token generation.
:param: is_registration_token: Indicates that the token will be
used only for email-based
registration
:param: custom_claims: Additional claims that should
be packed in the payload. Note that
any claims supplied here must be
JSON compatible types
"""
ClaimCollisionError.require_condition(
set(custom_claims.keys()).isdisjoint(RESERVED_CLAIMS),
"The custom claims collide with required claims",
)
if not bypass_user_check:
self._check_user(user)
moment = pendulum.now('UTC')
if override_refresh_lifespan is None:
refresh_lifespan = self.refresh_lifespan
else:
refresh_lifespan = override_refresh_lifespan
refresh_expiration = (moment + refresh_lifespan).int_timestamp
if override_access_lifespan is None:
access_lifespan = self.access_lifespan
else:
access_lifespan = override_access_lifespan
access_expiration = min(
(moment + access_lifespan).int_timestamp,
refresh_expiration,
)
payload_parts = {
'iat': moment.int_timestamp,
'exp': access_expiration,
'jti': str(uuid.uuid4()),
'id': user.identity,
'rls': ','.join(user.rolenames),
REFRESH_EXPIRATION_CLAIM: refresh_expiration,
}
if is_registration_token:
payload_parts[IS_REGISTRATION_TOKEN_CLAIM] = True
if is_reset_token:
payload_parts[IS_RESET_TOKEN_CLAIM] = True
flask.current_app.logger.debug(
"Attaching custom claims: {}".format(custom_claims), )
payload_parts.update(custom_claims)
if self.encode_jwt_token_hook:
self.encode_jwt_token_hook(**payload_parts)
return jwt.encode(
payload_parts,
self.encode_key,
self.encode_algorithm,
).decode('utf-8')
def encode_eternal_jwt_token(self, user, **custom_claims):
"""
This utility function encodes a jwt token that never expires
.. note:: This should be used sparingly since the token could become
a security concern if it is ever lost. If you use this
method, you should be sure that your application also
implements a blacklist so that a given token can be blocked
should it be lost or become a security concern
"""
return self.encode_jwt_token(user,
override_access_lifespan=VITAM_AETERNUM,
override_refresh_lifespan=VITAM_AETERNUM,
**custom_claims)
def refresh_jwt_token(self, token, override_access_lifespan=None):
"""
Creates a new token for a user if and only if the old token's access
permission is expired but its refresh permission is not yet expired.
The new token's refresh expiration moment is the same as the old
token's, but the new token's access expiration is refreshed
:param: token: The existing jwt token that needs to
be replaced with a new, refreshed
token
:param: override_access_lifespan: Override's the instance's access
lifespan to set a custom duration
after which the new token's
accessability will expire. May not
exceed the refresh lifespan
"""
moment = pendulum.now('UTC')
data = self.extract_jwt_token(token, access_type=AccessType.refresh)
user = self.user_class.identify(data['id'])
self._check_user(user)
if override_access_lifespan is None:
access_lifespan = self.access_lifespan
else:
access_lifespan = override_access_lifespan
refresh_expiration = data[REFRESH_EXPIRATION_CLAIM]
access_expiration = min(
(moment + access_lifespan).int_timestamp,
refresh_expiration,
)
custom_claims = {
k: v
for (k, v) in data.items() if k not in RESERVED_CLAIMS
}
payload_parts = {
'iat': moment.int_timestamp,
'exp': access_expiration,
'jti': data['jti'],
'id': data['id'],
'rls': ','.join(user.rolenames),
REFRESH_EXPIRATION_CLAIM: refresh_expiration,
}
payload_parts.update(custom_claims)
if self.refresh_jwt_token_hook:
self.refresh_jwt_token_hook(**payload_parts)
return jwt.encode(
payload_parts,
self.encode_key,
self.encode_algorithm,
).decode('utf-8')
def extract_jwt_token(self, token, access_type=AccessType.access):
"""
Extracts a data dictionary from a jwt token
"""
# Note: we disable exp verification because we will do it ourselves
with InvalidTokenHeader.handle_errors('failed to decode JWT token'):
data = jwt.decode(
token,
self.encode_key,
algorithms=self.allowed_algorithms,
options={'verify_exp': False},
)
self._validate_jwt_data(data, access_type=access_type)
return data
def _validate_jwt_data(self, data, access_type):
"""
Validates that the data for a jwt token is valid
"""
MissingClaimError.require_condition(
'jti' in data,
'Token is missing jti claim',
)
BlacklistedError.require_condition(
not self.is_blacklisted(data['jti']),
'Token has a blacklisted jti',
)
MissingClaimError.require_condition(
'id' in data,
'Token is missing id field',
)
MissingClaimError.require_condition(
'exp' in data,
'Token is missing exp claim',
)
MissingClaimError.require_condition(
REFRESH_EXPIRATION_CLAIM in data,
'Token is missing {} claim'.format(REFRESH_EXPIRATION_CLAIM),
)
moment = pendulum.now('UTC').int_timestamp
if access_type == AccessType.access:
MisusedRegistrationToken.require_condition(
IS_REGISTRATION_TOKEN_CLAIM not in data,
"registration token used for access")
MisusedResetToken.require_condition(
IS_RESET_TOKEN_CLAIM not in data,
"password reset token used for access")
ExpiredAccessError.require_condition(
moment <= data['exp'],
'access permission has expired',
)
elif access_type == AccessType.refresh:
MisusedRegistrationToken.require_condition(
IS_REGISTRATION_TOKEN_CLAIM not in data,
"registration token used for refresh")
MisusedResetToken.require_condition(
IS_RESET_TOKEN_CLAIM not in data,
"password reset token used for refresh")
EarlyRefreshError.require_condition(
moment > data['exp'],
'access permission for token has not expired. may not refresh',
)
ExpiredRefreshError.require_condition(
moment <= data[REFRESH_EXPIRATION_CLAIM],
'refresh permission for token has expired',
)
elif access_type == AccessType.register:
ExpiredAccessError.require_condition(
moment <= data['exp'],
'register permission has expired',
)
InvalidRegistrationToken.require_condition(
IS_REGISTRATION_TOKEN_CLAIM in data,
"invalid registration token used for verification")
MisusedResetToken.require_condition(
IS_RESET_TOKEN_CLAIM not in data,
"password reset token used for registration")
elif access_type == AccessType.reset:
MisusedRegistrationToken.require_condition(
IS_REGISTRATION_TOKEN_CLAIM not in data,
"registration token used for reset")
ExpiredAccessError.require_condition(
moment <= data['exp'],
'reset permission has expired',
)
InvalidResetToken.require_condition(
IS_RESET_TOKEN_CLAIM in data,
"invalid reset token used for verification")
def _unpack_header(self, headers):
"""
Unpacks a jwt token from a request header
"""
jwt_header = headers.get(self.header_name)
MissingToken.require_condition(
jwt_header is not None,
"JWT token not found in headers under '{}'".format(
self.header_name, ),
)
match = re.match(self.header_type + r'\s*([\w\.-]+)', jwt_header)
InvalidTokenHeader.require_condition(
match is not None,
"JWT header structure is invalid",
)
token = match.group(1)
return token
def read_token_from_header(self):
"""
Unpacks a jwt token from the current flask request
"""
return self._unpack_header(flask.request.headers)
def _unpack_cookie(self, cookies):
"""
Unpacks a jwt token from a request cookies
"""
jwt_cookie = cookies.get(self.cookie_name)
MissingToken.require_condition(
jwt_cookie is not None,
"JWT token not found in cookie under '{}'".format(
self.cookie_name),
)
return jwt_cookie
def read_token_from_cookie(self):
"""
Unpacks a jwt token from the current flask request
"""
return self._unpack_cookie(flask.request.cookies)
def read_token(self):
exc = None
if 'header' in self.jwt_places:
try:
return self.read_token_from_header()
except MissingToken as e:
exc = e
if 'cookie' in self.jwt_places:
try:
return self.read_token_from_cookie()
except MissingToken as e:
exc = e
if exc:
raise MissingToken("JWT token not found in {}".format(
self.jwt_places))
def pack_header_for_user(self,
user,
override_access_lifespan=None,
override_refresh_lifespan=None,
**custom_claims):
"""
Encodes a jwt token and packages it into a header dict for a given user
:param: user: The user to package the header for
:param: override_access_lifespan: Override's the instance's access
lifespan to set a custom duration
after which the new token's
accessability will expire. May not
exceed the refresh_lifespan
:param: override_refresh_lifespan: Override's the instance's refresh
lifespan to set a custom duration
after which the new token's
refreshability will expire.
:param: custom_claims: Additional claims that should
be packed in the payload. Note that
any claims supplied here must be
JSON compatible types
"""
token = self.encode_jwt_token(
user,
override_access_lifespan=override_access_lifespan,
override_refresh_lifespan=override_refresh_lifespan,
**custom_claims)
return {self.header_name: self.header_type + ' ' + token}
def send_registration_email(self,
email,
user=None,
template=None,
confirmation_sender=None,
confirmation_uri=None,
subject=None,
override_access_lifespan=None):
"""
Sends a registration email to a new user, containing a time expiring
token usable for validation. This requires your application
is initialized with a `mail` extension, which supports
Flask-Mail's `Message()` object and a `send()` method.
Returns a dict containing the information sent, along with the
`result` from mail send.
:param: user: The user object to tie claim to
(username, id, email, etc)
:param: template: HTML Template for confirmation email.
If not provided, a stock entry is
used
:param: confirmation_sender: The sender that shoudl be attached
to the confirmation email. Overrides
the PRAETORIAN_CONFIRMRATION_SENDER
config setting
:param: confirmation_uri: The uri that should be visited to
complete email registration. Should
usually be a uri to a frontend or
external service that calls a
'finalize' method in the api to
complete registration. Will override
the PRAETORIAN_CONFIRMATION_URI
config setting
:param: subject: The registration email subject.
Will override the
PRAETORIAN_CONFIRMATION_SUBJECT
config setting.
:param: override_access_lifespan: Overrides the JWT_ACCESS_LIFESPAN
to set an access lifespan for the
registration token.
"""
if subject is None:
subject = self.confirmation_subject
if confirmation_uri is None:
confirmation_uri = self.confirmation_uri
sender = confirmation_sender or self.confirmation_sender
flask.current_app.logger.debug(
"Generating token with lifespan: {}".format(
override_access_lifespan))
custom_token = self.encode_jwt_token(
user,
override_access_lifespan=override_access_lifespan,
bypass_user_check=True,
is_registration_token=True,
)
return self.send_token_email(email,
user,
template,
confirmation_sender,
confirmation_uri,
subject,
custom_token=custom_token,
sender=sender)
def send_reset_email(self,
email,
template=None,
reset_sender=None,
reset_uri=None,
subject=None,
override_access_lifespan=None):
"""
Sends a password reset email to a user, containing a time expiring
token usable for validation. This requires your application
is initialized with a `mail` extension, which supports
Flask-Mail's `Message()` object and a `send()` method.
Returns a dict containing the information sent, along with the
`result` from mail send.
:param: email: The email address to attempt to
send to
:param: template: HTML Template for reset email.
If not provided, a stock entry is
used
:param: confirmation_sender: The sender that shoudl be attached
to the reset email. Overrides
the PRAETORIAN_RESET_SENDER
config setting
:param: confirmation_uri: The uri that should be visited to
complete password reset. Should
usually be a uri to a frontend or
external service that calls the
'validate_reset_token()' method in
the api to complete reset. Will
override the PRAETORIAN_RESET_URI
config setting
:param: subject: The reset email subject.
Will override the
PRAETORIAN_RESET_SUBJECT
config setting.
:param: override_access_lifespan: Overrides the JWT_ACCESS_LIFESPAN
to set an access lifespan for the
registration token.
"""
if subject is None:
subject = self.reset_subject
if reset_uri is None:
reset_uri = self.reset_uri
sender = reset_sender or self.reset_sender
user = self.user_class.lookup(email)
MissingUserError.require_condition(
user is not None,
'Could not find the requested user',
)
flask.current_app.logger.debug(
"Generating token with lifespan: {}".format(
override_access_lifespan))
custom_token = self.encode_jwt_token(
user,
override_access_lifespan=override_access_lifespan,
bypass_user_check=False,
is_reset_token=True,
)
return self.send_token_email(user.email,
user,
template,
reset_sender,
reset_uri,
subject,
custom_token=custom_token,
sender=sender)
def send_token_email(self,
email,
user=None,
template=None,
action_sender=None,
action_uri=None,
subject=None,
override_access_lifespan=None,
custom_token=None,
sender='no-reply@praetorian'):
"""
Sends an email to a user, containing a time expiring
token usable for several actions. This requires
your application is initialized with a `mail` extension,
which supports Flask-Mail's `Message()` object and
a `send()` method.
Returns a dict containing the information sent, along with the
`result` from mail send.
:param: email: The email address to use
(username, id, email, etc)
:param: user: The user object to tie claim to
(username, id, email, etc)
:param: template: HTML Template for confirmation email.
If not provided, a stock entry is
used
:param: action_sender: The sender that should be attached
to the confirmation email.
:param: action_uri: The uri that should be visited to
complete the token action.
:param: subject: The email subject.
:param: override_access_lifespan: Overrides the JWT_ACCESS_LIFESPAN
to set an access lifespan for the
registration token.
"""
notification = {
'result': None,
'message': None,
'user': str(user),
'email': email,
'token': custom_token,
'subject': subject,
'confirmation_uri': action_uri, # backwards compatibility
'action_uri': action_uri,
}
PraetorianError.require_condition(
action_sender,
"A sender is required to send confirmation email",
)
PraetorianError.require_condition(
custom_token,
"A custom_token is required to send notification email",
)
if template is None:
with open(self.confirmation_template) as fh:
template = fh.read()
with PraetorianError.handle_errors('fail sending email'):
flask.current_app.logger.debug(
"NOTIFICATION: {}".format(notification))
jinja_tmpl = jinja2.Template(template)
notification['message'] = jinja_tmpl.render(notification).strip()
msg = Message(html=notification['message'],
sender=action_sender,
subject=notification['subject'],
recipients=[notification['email']])
flask.current_app.logger.debug("Sending email to {}".format(email))
notification['result'] = flask.current_app.extensions['mail'].send(
msg)
return notification
def get_user_from_registration_token(self, token):
"""
Gets a user based on the registration token that is supplied. Verifies
that the token is a regisration token and that the user can be properly
retrieved
"""
data = self.extract_jwt_token(token, access_type=AccessType.register)
flask.current_app.logger.debug("DATA: {}".format(data))
user_id = data.get('id')
PraetorianError.require_condition(
user_id is not None,
"Could not fetch an id from the registration token",
)
user = self.user_class.identify(user_id)
PraetorianError.require_condition(
user is not None,
"Could not identify the user from the registration token",
)
return user
def validate_reset_token(self, token):
"""
Validates a password reset request based on the reset token
that is supplied. Verifies that the token is a reset token
and that the user can be properly retrieved
"""
data = self.extract_jwt_token(token, access_type=AccessType.reset)
user_id = data.get('id')
PraetorianError.require_condition(
user_id is not None,
"Could not fetch an id from the reset token",
)
user = self.user_class.identify(user_id)
PraetorianError.require_condition(
user is not None,
"Could not identify the user from the reset token",
)
return user
def hash_password(self, raw_password):
"""
Hashes a plaintext password using the stored passlib password context
"""
PraetorianError.require_condition(
self.pwd_ctx is not None,
"Praetorian must be initialized before this method is available",
)
"""
`scheme` is now set with self.pwd_ctx.update(default=scheme) due
to the depreciation in upcoming passlib 2.0.
zillions of warnings suck.
"""
return self.pwd_ctx.hash(raw_password)
def verify_and_update(self, user=None, password=None):
"""
Validate a password hash contained in the user object is
hashed with the defined hash scheme (PRAETORIAN_HASH_SCHEME).
If not, raise an Exception of `LegacySchema`, unless the
`password` arguement is provided, in which case an attempt
to call `user.save()` will be made, updating the hashed
password to the currently desired hash scheme
(PRAETORIAN_HASH_SCHEME).
:param: user: The user object to tie claim to
(username, id, email, etc). *MUST*
include the hashed password field,
defined as `user.password`
:param: password: The user's provide password from login.
If present, this is used to validate
and then attempt to update with the
new PRAETORIAN_HASH_SCHEME scheme.
"""
if self.pwd_ctx.needs_update(user.password):
if password:
(rv, updated) = self.pwd_ctx.verify_and_update(
password,
user.password,
)
AuthenticationError.require_condition(
rv,
"Could not verify password",
)
user.password = updated
else:
used_hash = self.pwd_ctx.identify(user.password)
desired_hash = self.hash_scheme
raise LegacyScheme("Hash using non-current scheme '{}'."
"Use '{}' instead.".format(
used_hash, desired_hash))
return user
class Praetorian:
"""
Comprises the implementation for the flask-praetorian flask extension.
Provides a tool that allows password authentication and token provision
for applications and designated endpoints
"""
def __init__(self, app=None, user_class=None, is_blacklisted=None):
self.pwd_ctx = None
self.hash_scheme = None
self.salt = None
if app is not None and user_class is not None:
self.init_app(app, user_class, is_blacklisted)
def init_app(self, app, user_class, is_blacklisted=None):
"""
Initializes the Praetorian extension
:param: app: The flask app to bind this extension to
:param: user_class: The class used to interact with user data
:param: is_blacklisted: A method that may optionally be used to
check the token against a blacklist when
access or refresh is requested
Should take the jti for the token to check
as a single argument. Returns True if
the jti is blacklisted, False otherwise.
By default, always returns False.
"""
PraetorianError.require_condition(
app.config.get('SECRET_KEY') is not None,
"There must be a SECRET_KEY app config setting set",
)
possible_schemes = [
'argon2',
'bcrypt',
'pbkdf2_sha512',
]
self.pwd_ctx = CryptContext(
default='pbkdf2_sha512',
schemes=possible_schemes + ['plaintext'],
deprecated=[],
)
self.hash_scheme = app.config.get('PRAETORIAN_HASH_SCHEME')
valid_schemes = self.pwd_ctx.schemes()
PraetorianError.require_condition(
self.hash_scheme in valid_schemes or self.hash_scheme is None,
"If {} is set, it must be one of the following schemes: {}",
'PRAETORIAN_HASH_SCHEME',
valid_schemes,
)
self.user_class = self._validate_user_class(user_class)
self.is_blacklisted = is_blacklisted or (lambda t: False)
self.encode_key = app.config['SECRET_KEY']
self.allowed_algorithms = app.config.get(
'JWT_ALLOWED_ALGORITHMS',
DEFAULT_JWT_ALLOWED_ALGORITHMS,
)
self.encode_algorithm = app.config.get(
'JWT_ALGORITHM',
DEFAULT_JWT_ALGORITHM,
)
self.access_lifespan = pendulum.Duration(**app.config.get(
'JWT_ACCESS_LIFESPAN',
DEFAULT_JWT_ACCESS_LIFESPAN,
))
self.refresh_lifespan = pendulum.Duration(**app.config.get(
'JWT_REFRESH_LIFESPAN',
DEFAULT_JWT_REFRESH_LIFESPAN,
))
self.header_name = app.config.get(
'JWT_HEADER_NAME',
DEFAULT_JWT_HEADER_NAME,
)
self.header_type = app.config.get(
'JWT_HEADER_TYPE',
DEFAULT_JWT_HEADER_TYPE,
)
self.user_class_validation_method = app.config.get(
'USER_CLASS_VALIDATION_METHOD',
DEFAULT_USER_CLASS_VALIDATION_METHOD,
)
if not app.config.get('DISABLE_PRAETORIAN_ERROR_HANDLER'):
app.register_error_handler(
PraetorianError,
PraetorianError.build_error_handler(),
)
self.is_testing = app.config.get('TESTING', False)
if not hasattr(app, 'extensions'):
app.extensions = {}
app.extensions['praetorian'] = self
@classmethod
def _validate_user_class(cls, user_class):
"""
Validates the supplied user_class to make sure that it has the
class methods necessary to function correctly.
Requirements:
- ``lookup`` method. Accepts a string parameter, returns instance
- ``identify`` method. Accepts an identity parameter, returns instance
"""
PraetorianError.require_condition(
getattr(user_class, 'lookup', None) is not None,
textwrap.dedent("""
The user_class must have a lookup class method:
user_class.lookup(<str>) -> <user instance>
"""),
)
PraetorianError.require_condition(
getattr(user_class, 'identify', None) is not None,
textwrap.dedent("""
The user_class must have an identify class method:
user_class.identify(<identity>) -> <user instance>
"""),
)
# TODO: Figure out how to check for an identity property
return user_class
def authenticate(self, username, password):
"""
Verifies that a password matches the stored password for that username.
If verification passes, the matching user instance is returned
"""
PraetorianError.require_condition(
self.user_class is not None,
"Praetorian must be initialized before this method is available",
)
user = self.user_class.lookup(username)
MissingUserError.require_condition(
user is not None,
'Could not find the requested user',
)
AuthenticationError.require_condition(
self._verify_password(password, user.password),
'The password is incorrect',
)
return user
def _verify_password(self, raw_password, hashed_password):
"""
Verifies that a plaintext password matches the hashed version of that
password using the stored passlib password context
"""
PraetorianError.require_condition(
self.pwd_ctx is not None,
"Praetorian must be initialized before this method is available",
)
return self.pwd_ctx.verify(raw_password, hashed_password)
def encrypt_password(self, raw_password):
"""
Encrypts a plaintext password using the stored passlib password context
"""
PraetorianError.require_condition(
self.pwd_ctx is not None,
"Praetorian must be initialized before this method is available",
)
return self.pwd_ctx.encrypt(raw_password, scheme=self.hash_scheme)
def error_handler(self, error):
"""
Provides a flask error handler that is used for PraetorianErrors
(and derived exceptions).
"""
warnings.warn(
"""
error_handler is deprecated.
Use FlaskBuzz.build_error_handler instead
""",
warnings.DeprecationWarning,
)
return error.jsonify(), error.status_code, error.headers
def _check_user(self, user):
"""
Checks to make sure that a user is valid. First, checks that the user
is not None. If this check fails, a MissingUserError is raised. Next,
checks if the user has a validation method. If the method does not
exist, the check passes. If the method exists, it is called. If the
result of the call is not truthy, an InvalidUserError is raised
"""
MissingUserError.require_condition(
user is not None,
'Could not find the requested user',
)
user_validate_method = getattr(user, self.user_class_validation_method,
None)
if user_validate_method is None:
return
InvalidUserError.require_condition(
user_validate_method(),
"The user is not valid or has had access revoked",
)
def encode_jwt_token(self,
user,
override_access_lifespan=None,
override_refresh_lifespan=None,
**custom_claims):
"""
Encodes user data into a jwt token that can be used for authorization
at protected endpoints
:param: override_access_lifespan: Override's the instance's access
lifespan to set a custom duration
after which the new token's
accessability will expire. May not
exceed the refresh_lifespan
:param: override_refresh_lifespan: Override's the instance's refresh
lifespan to set a custom duration
after which the new token's
refreshability will expire.
:param: custom_claims: Additional claims that should
be packed in the payload. Note that
any claims supplied here must be
JSON compatible types
"""
ClaimCollisionError.require_condition(
set(custom_claims.keys()).isdisjoint(RESERVED_CLAIMS),
"The custom claims collide with required claims",
)
self._check_user(user)
moment = pendulum.now('UTC')
if override_refresh_lifespan is None:
refresh_lifespan = self.refresh_lifespan
else:
refresh_lifespan = override_refresh_lifespan
refresh_expiration = (moment + refresh_lifespan).int_timestamp
if override_access_lifespan is None:
access_lifespan = self.access_lifespan
else:
access_lifespan = override_access_lifespan
access_expiration = min(
(moment + access_lifespan).int_timestamp,
refresh_expiration,
)
payload_parts = dict(iat=moment.int_timestamp,
exp=access_expiration,
rf_exp=refresh_expiration,
jti=str(uuid.uuid4()),
id=user.identity,
rls=','.join(user.rolenames),
**custom_claims)
return jwt.encode(
payload_parts,
self.encode_key,
self.encode_algorithm,
).decode('utf-8')
def encode_eternal_jwt_token(self, user, **custom_claims):
"""
This utility function encodes a jwt token that never expires
.. note:: This should be used sparingly since the token could become
a security concern if it is ever lost. If you use this
method, you should be sure that your application also
implements a blacklist so that a given token can be blocked
should it be lost or become a security concern
"""
return self.encode_jwt_token(user,
override_access_lifespan=VITAM_AETERNUM,
override_refresh_lifespan=VITAM_AETERNUM,
**custom_claims)
def refresh_jwt_token(self, token, override_access_lifespan=None):
"""
Creates a new token for a user if and only if the old token's access
permission is expired but its refresh permission is not yet expired.
The new token's refresh expiration moment is the same as the old
token's, but the new token's access expiration is refreshed
:param: token: The existing jwt token that needs to
be replaced with a new, refreshed
token
:param: override_access_lifespan: Override's the instance's access
lifespan to set a custom duration
after which the new token's
accessability will expire. May not
exceed the refresh lifespan
"""
moment = pendulum.now('UTC')
# Note: we disable exp verification because we do custom checks here
with InvalidTokenHeader.handle_errors('failed to decode JWT token'):
data = jwt.decode(
token,
self.encode_key,
algorithms=self.allowed_algorithms,
options={'verify_exp': False},
)
self._validate_jwt_data(data, access_type=AccessType.refresh)
user = self.user_class.identify(data['id'])
self._check_user(user)
if override_access_lifespan is None:
access_lifespan = self.access_lifespan
else:
access_lifespan = override_access_lifespan
refresh_expiration = data['rf_exp']
access_expiration = min(
(moment + access_lifespan).int_timestamp,
refresh_expiration,
)
custom_claims = {
k: v
for (k, v) in data.items() if k not in RESERVED_CLAIMS
}
payload_parts = dict(iat=moment.int_timestamp,
exp=access_expiration,
rf_exp=refresh_expiration,
jti=data['jti'],
id=data['id'],
rls=','.join(user.rolenames),
**custom_claims)
return jwt.encode(
payload_parts,
self.encode_key,
self.encode_algorithm,
).decode('utf-8')
def extract_jwt_token(self, token):
"""
Extracts a data dictionary from a jwt token
"""
# Note: we disable exp verification because we will do it ourselves
with InvalidTokenHeader.handle_errors('failed to decode JWT token'):
data = jwt.decode(
token,
self.encode_key,
algorithms=self.allowed_algorithms,
options={'verify_exp': False},
)
self._validate_jwt_data(data, access_type=AccessType.access)
return data
def _validate_jwt_data(self, data, access_type):
"""
Validates that the data for a jwt token is valid
"""
MissingClaimError.require_condition(
'jti' in data,
'Token is missing jti claim',
)
BlacklistedError.require_condition(
not self.is_blacklisted(data['jti']),
'Token has a blacklisted jti',
)
MissingClaimError.require_condition(
'id' in data,
'Token is missing id field',
)
MissingClaimError.require_condition(
'exp' in data,
'Token is missing exp claim',
)
MissingClaimError.require_condition(
'rf_exp' in data,
'Token is missing rf_exp claim',
)
moment = pendulum.now('UTC').int_timestamp
if access_type == AccessType.access:
ExpiredAccessError.require_condition(
moment <= data['exp'],
'access permission has expired',
)
elif access_type == AccessType.refresh:
EarlyRefreshError.require_condition(
moment > data['exp'],
'access permission for token has not expired. may not refresh',
)
ExpiredRefreshError.require_condition(
moment <= data['rf_exp'],
'refresh permission for token has expired',
)
def _unpack_header(self, headers):
"""
Unpacks a jwt token from a request header
"""
jwt_header = headers.get(self.header_name)
MissingTokenHeader.require_condition(
jwt_header is not None,
"JWT token not found in headers under '{}'",
self.header_name,
)
match = re.match(self.header_type + r'\s*([\w\.-]+)', jwt_header)
InvalidTokenHeader.require_condition(
match is not None,
"JWT header structure is invalid",
)
token = match.group(1)
return token
def read_token_from_header(self):
"""
Unpacks a jwt token from the current flask request
"""
return self._unpack_header(flask.request.headers)
def pack_header_for_user(self,
user,
override_access_lifespan=None,
override_refresh_lifespan=None,
**custom_claims):
"""
Encodes a jwt token and packages it into a header dict for a given user
:param: user: The user to package the header for
:param: override_access_lifespan: Override's the instance's access
lifespan to set a custom duration
after which the new token's
accessability will expire. May not
exceed the refresh_lifespan
:param: override_refresh_lifespan: Override's the instance's refresh
lifespan to set a custom duration
after which the new token's
refreshability will expire.
:param: custom_claims: Additional claims that should
be packed in the payload. Note that
any claims supplied here must be
JSON compatible types
"""
token = self.encode_jwt_token(
user,
override_access_lifespan=override_access_lifespan,
override_refresh_lifespan=override_refresh_lifespan,
**custom_claims)
return {self.header_name: self.header_type + ' ' + token}
class Praetorian:
"""
Comprises the implementation for the flask-praetorian flask extension.
Provides a tool that allows password authentication and token provision
for applications and designated endpoints
"""
def __init__(self, app=None, user_class=None, is_blacklisted=None):
self.pwd_ctx = None
self.hash_scheme = None
self.salt = None
if app is not None and user_class is not None:
self.init_app(app, user_class, is_blacklisted)
def init_app(self, app, user_class, is_blacklisted=None):
"""
Initializes the Praetorian extension
:param: app: The flask app to bind this extension to
:param: user_class: The class used to interact with user data
:param: is_blacklisted: A method that may optionally be used to
check the token against a blacklist when
access or refresh is requested
Should take the jti for the token to check
as a single argument. Returns True if
the jti is blacklisted, False otherwise.
By default, always returns False.
"""
PraetorianError.require_condition(
app.config.get('SECRET_KEY') is not None,
"There must be a SECRET_KEY app config setting set",
)
possible_schemes = [
'argon2',
'bcrypt',
'pbkdf2_sha512',
]
self.pwd_ctx = CryptContext(
default='bcrypt',
schemes=possible_schemes + ['plaintext'],
deprecated=[],
)
self.hash_scheme = app.config.get('PRAETORIAN_HASH_SCHEME')
valid_schemes = self.pwd_ctx.schemes()
PraetorianError.require_condition(
self.hash_scheme in valid_schemes or self.hash_scheme is None,
"If {} is set, it must be one of the following schemes: {}",
'PRAETORIAN_HASH_SCHEME',
valid_schemes,
)
self.user_class = self.validate_user_class(user_class)
self.is_blacklisted = is_blacklisted or (lambda t: False)
self.encode_key = app.config['SECRET_KEY']
self.allowed_algorithms = app.config.get(
'JWT_ALLOWED_ALGORITHMS',
DEFAULT_JWT_ALLOWED_ALGORITHMS,
)
self.encode_algorithm = app.config.get(
'JWT_ALGORITHM',
DEFAULT_JWT_ALGORITHM,
)
self.access_lifespan = app.config.get(
'JWT_ACCESS_LIFESPAN',
DEFAULT_JWT_ACCESS_LIFESPAN,
)
self.refresh_lifespan = app.config.get(
'JWT_REFRESH_LIFESPAN',
DEFAULT_JWT_REFRESH_LIFESPAN,
)
self.header_name = app.config.get(
'JWT_HEADER_NAME',
DEFAULT_JWT_HEADER_NAME,
)
self.header_type = app.config.get(
'JWT_HEADER_TYPE',
DEFAULT_JWT_HEADER_TYPE,
)
app.errorhandler(PraetorianError)(self.error_handler)
self.is_testing = app.config.get('TESTING', False)
if not hasattr(app, 'extensions'):
app.extensions = {}
app.extensions['praetorian'] = self
@classmethod
def validate_user_class(cls, user_class):
"""
Validates the supplied user_class to make sure that it has the
class methods necessary to function correctly.
Requirements:
- ``lookup`` method. Accepts a string parameter, returns instance
- ``identify`` method. Accepts an identity parameter, returns instance
"""
PraetorianError.require_condition(
getattr(user_class, 'lookup', None) is not None,
textwrap.dedent("""
The user_class must have a lookup class method:
user_class.lookup(<str>) -> <user instance>
"""),
)
PraetorianError.require_condition(
getattr(user_class, 'identify', None) is not None,
textwrap.dedent("""
The user_class must have an identify class method:
user_class.identify(<identity>) -> <user instance>
"""),
)
# TODO: Figure out how to check for an identity property
return user_class
def authenticate(self, username, password):
"""
Verifies that a password matches the stored password for that username.
If verification passes, the matching user instance is returned
"""
PraetorianError.require_condition(
self.user_class is not None,
"Praetorian must be initialized before this method is available",
)
user = self.user_class.lookup(username)
if user is None or not self.verify_password(password, user.password):
return None
return user
def verify_password(self, raw_password, hashed_password):
"""
Verifies that a plaintext password matches the hashed version of that
password using the stored passlib password context
"""
PraetorianError.require_condition(
self.pwd_ctx is not None,
"Praetorian must be initialized before this method is available",
)
return self.pwd_ctx.verify(raw_password, hashed_password)
def encrypt_password(self, raw_password):
"""
Encrypts a plaintext password using the stored passlib password context
"""
PraetorianError.require_condition(
self.pwd_ctx is not None,
"Praetorian must be initialized before this method is available",
)
return self.pwd_ctx.encrypt(raw_password, scheme=self.hash_scheme)
def error_handler(self, error):
"""
Provides a flask error handler that is used for PraetorianErrors
(and derived exceptions).
"""
return error.jsonify(), error.status_code, error.headers
def encode_jwt_token(self, user):
"""
Encodes user data into a jwt token that can be used for authorization
at protected endpoints
"""
moment = pendulum.utcnow()
payload_parts = dict(
iat=moment.int_timestamp,
exp=(moment + self.access_lifespan).int_timestamp,
rf_exp=(moment + self.refresh_lifespan).int_timestamp,
jti=str(uuid.uuid4()),
id=user.identity,
rls=','.join(user.rolenames),
)
return jwt.encode(
payload_parts,
self.encode_key,
self.encode_algorithm,
).decode('utf-8')
def refresh_jwt_token(self, token):
"""
Creates a new token for a user if and only if the old token's access
permission is expired but its refresh permission is not yet expired.
The new token's refresh expiration moment is the same as the old
token's, but the new token's access expiration is refreshed
"""
moment = datetime.datetime.utcnow()
# Note: we disable exp verification because we do custom checks here
data = jwt.decode(
token,
self.encode_key,
algorithms=self.allowed_algorithms,
options={'verify_exp': False},
)
self.validate_jwt_data(data, access_type=AccessType.refresh)
user = self.user_class.identify(data['id'])
PraetorianError.require_condition(
user is not None,
'Could not find an active user for the token',
)
payload_parts = dict(
iat=moment,
exp=moment + self.access_lifespan,
rf_exp=data['rf_exp'],
jti=data['jti'],
id=data['id'],
rls=','.join(user.rolenames),
)
return jwt.encode(
payload_parts,
self.encode_key,
self.encode_algorithm,
).decode('utf-8')
def extract_jwt_token(self, token):
"""
Extracts a data dictionary from a jwt token
"""
# Note: we disable exp verification because we will do it ourselves
with PraetorianError.handle_errors('failed to decode JWT token'):
data = jwt.decode(
token,
self.encode_key,
algorithms=self.allowed_algorithms,
options={'verify_exp': False},
)
self.validate_jwt_data(data, access_type=AccessType.access)
return data
def validate_jwt_data(self, data, access_type):
"""
Validates that the data for a jwt token is valid
"""
MissingClaimError.require_condition(
'jti' in data,
'Token is missing jti claim',
)
BlacklistedError.require_condition(
not self.is_blacklisted(data['jti']),
'Token has a blacklisted jti',
)
MissingClaimError.require_condition(
'id' in data,
'Token is missing id field',
)
MissingClaimError.require_condition(
'exp' in data,
'Token is missing exp claim',
)
MissingClaimError.require_condition(
'rf_exp' in data,
'Token is missing rf_exp claim',
)
moment = pendulum.utcnow().int_timestamp
if access_type == AccessType.access:
ExpiredAccessError.require_condition(
moment <= data['exp'],
'access permission has expired',
)
elif access_type == AccessType.refresh:
EarlyRefreshError.require_condition(
moment > data['exp'],
'access permission for token has not expired. may not refresh',
)
ExpiredRefreshError.require_condition(
moment <= data['rf_exp'],
'refresh permission for token has expired',
)
def unpack_header(self, headers):
"""
Unpacks a jwt token from a request header
"""
jwt_header = headers.get(self.header_name)
MissingTokenHeader.require_condition(
jwt_header is not None,
"JWT token not found in headers under '{}'",
self.header_name,
)
match = re.match(self.header_type + r'\s*([\w\.-]+)', jwt_header)
InvalidTokenHeader.require_condition(
match is not None,
"JWT header structure is invalid",
)
token = match.group(1)
return token
def read_token_from_header(self):
"""
Unpacks a jwt token from the current flask request
"""
return self.unpack_header(flask.request.headers)
def pack_header_for_user(self, user):
"""
A method that may only be used for testing that packages a jwt token
into a header dict for a given user
"""
PraetorianError.require_condition(
self.is_testing,
"Pack header may only be used for testing",
)
token = self.encode_jwt_token(user)
return {self.header_name: self.header_type + ' ' + token}