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security.py
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security.py
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from zope.interface import providedBy
from pyramid.interfaces import (
IAuthenticationPolicy,
IAuthorizationPolicy,
ISecuredView,
IViewClassifier,
)
from pyramid.compat import map_
from pyramid.threadlocal import get_current_registry
Everyone = 'system.Everyone'
Authenticated = 'system.Authenticated'
Allow = 'Allow'
Deny = 'Deny'
class AllPermissionsList(object):
""" Stand in 'permission list' to represent all permissions """
def __iter__(self):
return ()
def __contains__(self, other):
return True
def __eq__(self, other):
return isinstance(other, self.__class__)
ALL_PERMISSIONS = AllPermissionsList()
DENY_ALL = (Deny, Everyone, ALL_PERMISSIONS)
NO_PERMISSION_REQUIRED = '__no_permission_required__'
def has_permission(permission, context, request):
""" Provided a permission (a string or unicode object), a context
(a :term:`resource` instance) and a request object, return an
instance of :data:`pyramid.security.Allowed` if the permission
is granted in this context to the user implied by the
request. Return an instance of :mod:`pyramid.security.Denied`
if this permission is not granted in this context to this user.
This function delegates to the current authentication and
authorization policies. Return
:data:`pyramid.security.Allowed` unconditionally if no
authentication policy has been configured in this application."""
try:
reg = request.registry
except AttributeError:
reg = get_current_registry() # b/c
authn_policy = reg.queryUtility(IAuthenticationPolicy)
if authn_policy is None:
return Allowed('No authentication policy in use.')
authz_policy = reg.queryUtility(IAuthorizationPolicy)
if authz_policy is None:
raise ValueError('Authentication policy registered without '
'authorization policy') # should never happen
principals = authn_policy.effective_principals(request)
return authz_policy.permits(context, principals, permission)
def authenticated_userid(request):
""" Return the userid of the currently authenticated user or
``None`` if there is no :term:`authentication policy` in effect or
there is no currently authenticated user."""
try:
reg = request.registry
except AttributeError:
reg = get_current_registry() # b/c
policy = reg.queryUtility(IAuthenticationPolicy)
if policy is None:
return None
return policy.authenticated_userid(request)
def unauthenticated_userid(request):
""" Return an object which represents the *claimed* (not verified) user
id of the credentials present in the request. ``None`` if there is no
:term:`authentication policy` in effect or there is no user data
associated with the current request. This differs from
:func:`~pyramid.security.authenticated_userid`, because the effective
authentication policy will not ensure that a record associated with the
userid exists in persistent storage."""
try:
reg = request.registry
except AttributeError:
reg = get_current_registry() # b/c
policy = reg.queryUtility(IAuthenticationPolicy)
if policy is None:
return None
return policy.unauthenticated_userid(request)
def effective_principals(request):
""" Return the list of 'effective' :term:`principal` identifiers
for the ``request``. This will include the userid of the
currently authenticated user if a user is currently
authenticated. If no :term:`authentication policy` is in effect,
this will return an empty sequence."""
try:
reg = request.registry
except AttributeError:
reg = get_current_registry() # b/c
policy = reg.queryUtility(IAuthenticationPolicy)
if policy is None:
return [Everyone]
return policy.effective_principals(request)
def principals_allowed_by_permission(context, permission):
""" Provided a ``context`` (a resource object), and a ``permission``
(a string or unicode object), if a :term:`authorization policy` is
in effect, return a sequence of :term:`principal` ids that possess
the permission in the ``context``. If no authorization policy is
in effect, this will return a sequence with the single value
:mod:`pyramid.security.Everyone` (the special principal
identifier representing all principals).
.. note::
even if an :term:`authorization policy` is in effect,
some (exotic) authorization policies may not implement the
required machinery for this function; those will cause a
:exc:`NotImplementedError` exception to be raised when this
function is invoked.
"""
reg = get_current_registry()
policy = reg.queryUtility(IAuthorizationPolicy)
if policy is None:
return [Everyone]
return policy.principals_allowed_by_permission(context, permission)
def view_execution_permitted(context, request, name=''):
""" If the view specified by ``context`` and ``name`` is protected
by a :term:`permission`, check the permission associated with the
view using the effective authentication/authorization policies and
the ``request``. Return a boolean result. If no
:term:`authorization policy` is in effect, or if the view is not
protected by a permission, return ``True``."""
try:
reg = request.registry
except AttributeError:
reg = get_current_registry() # b/c
provides = [IViewClassifier] + map_(providedBy, (request, context))
view = reg.adapters.lookup(provides, ISecuredView, name=name)
if view is None:
return Allowed(
'Allowed: view name %r in context %r (no permission defined)' %
(name, context))
return view.__permitted__(context, request)
def remember(request, principal, **kw):
""" Return a sequence of header tuples (e.g. ``[('Set-Cookie',
'foo=abc')]``) suitable for 'remembering' a set of credentials
implied by the data passed as ``principal`` and ``*kw`` using the
current :term:`authentication policy`. Common usage might look
like so within the body of a view function (``response`` is
assumed to be a :term:`WebOb` -style :term:`response` object
computed previously by the view code)::
from pyramid.security import remember
headers = remember(request, 'chrism', password='123', max_age='86400')
response.headerlist.extend(headers)
return response
If no :term:`authentication policy` is in use, this function will
always return an empty sequence. If used, the composition and
meaning of ``**kw`` must be agreed upon by the calling code and
the effective authentication policy."""
try:
reg = request.registry
except AttributeError:
reg = get_current_registry() # b/c
policy = reg.queryUtility(IAuthenticationPolicy)
if policy is None:
return []
else:
return policy.remember(request, principal, **kw)
def forget(request):
""" Return a sequence of header tuples (e.g. ``[('Set-Cookie',
'foo=abc')]``) suitable for 'forgetting' the set of credentials
possessed by the currently authenticated user. A common usage
might look like so within the body of a view function
(``response`` is assumed to be an :term:`WebOb` -style
:term:`response` object computed previously by the view code)::
from pyramid.security import forget
headers = forget(request)
response.headerlist.extend(headers)
return response
If no :term:`authentication policy` is in use, this function will
always return an empty sequence."""
try:
reg = request.registry
except AttributeError:
reg = get_current_registry() # b/c
policy = reg.queryUtility(IAuthenticationPolicy)
if policy is None:
return []
else:
return policy.forget(request)
class PermitsResult(int):
def __new__(cls, s, *args):
inst = int.__new__(cls, cls.boolval)
inst.s = s
inst.args = args
return inst
@property
def msg(self):
return self.s % self.args
def __str__(self):
return self.msg
def __repr__(self):
return '<%s instance at %s with msg %r>' % (self.__class__.__name__,
id(self),
self.msg)
class Denied(PermitsResult):
""" An instance of ``Denied`` is returned when a security-related
API or other :app:`Pyramid` code denies an action unrelated to
an ACL check. It evaluates equal to all boolean false types. It
has an attribute named ``msg`` describing the circumstances for
the deny."""
boolval = 0
class Allowed(PermitsResult):
""" An instance of ``Allowed`` is returned when a security-related
API or other :app:`Pyramid` code allows an action unrelated to
an ACL check. It evaluates equal to all boolean true types. It
has an attribute named ``msg`` describing the circumstances for
the allow."""
boolval = 1
class ACLPermitsResult(int):
def __new__(cls, ace, acl, permission, principals, context):
inst = int.__new__(cls, cls.boolval)
inst.permission = permission
inst.ace = ace
inst.acl = acl
inst.principals = principals
inst.context = context
return inst
@property
def msg(self):
s = ('%s permission %r via ACE %r in ACL %r on context %r for '
'principals %r')
return s % (self.__class__.__name__,
self.permission,
self.ace,
self.acl,
self.context,
self.principals)
def __str__(self):
return self.msg
def __repr__(self):
return '<%s instance at %s with msg %r>' % (self.__class__.__name__,
id(self),
self.msg)
class ACLDenied(ACLPermitsResult):
""" An instance of ``ACLDenied`` represents that a security check made
explicitly against ACL was denied. It evaluates equal to all boolean
false types. It also has the following attributes: ``acl``, ``ace``,
``permission``, ``principals``, and ``context``. These attributes
indicate the security values involved in the request. Its __str__ method
prints a summary of these attributes for debugging purposes. The same
summary is available as the ``msg`` attribute."""
boolval = 0
class ACLAllowed(ACLPermitsResult):
""" An instance of ``ACLAllowed`` represents that a security check made
explicitly against ACL was allowed. It evaluates equal to all boolean
true types. It also has the following attributes: ``acl``, ``ace``,
``permission``, ``principals``, and ``context``. These attributes
indicate the security values involved in the request. Its __str__ method
prints a summary of these attributes for debugging purposes. The same
summary is available as the ``msg`` attribute."""
boolval = 1