nk20/apps/permission/signals.py

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# Copyright (C) 2018-2021 by BDE ENS Paris-Saclay
# SPDX-License-Identifier: GPL-3.0-or-later
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from django.core.exceptions import PermissionDenied
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from django.utils.translation import gettext_lazy as _
from note_kfet.middlewares import get_current_request
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from permission.backends import PermissionBackend
EXCLUDED = [
'cas_server.proxygrantingticket',
'cas_server.proxyticket',
'cas_server.serviceticket',
'cas_server.user',
'cas_server.userattributes',
'contenttypes.contenttype',
'logs.changelog',
'migrations.migration',
'oauth2_provider.accesstoken',
'oauth2_provider.grant',
'oauth2_provider.refreshtoken',
'sessions.session',
]
def pre_save_object(sender, instance, **kwargs):
"""
Before a model get saved, we check the permissions
"""
# noinspection PyProtectedMember
if instance._meta.label_lower in EXCLUDED:
return
if hasattr(instance, "_force_save") or hasattr(instance, "_no_signal"):
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return
request = get_current_request()
if request is None:
# Action performed on shell is always granted
return
qs = sender.objects.filter(pk=instance.pk).all()
model_name_full = instance._meta.label_lower.split(".")
app_label = model_name_full[0]
model_name = model_name_full[1]
if qs.exists():
# We check if the user can change the model
# If the user has all right on a model, then OK
if PermissionBackend.check_perm(request, app_label + ".change_" + model_name, instance):
return
# In the other case, we check if he/she has the right to change one field
previous = qs.get()
for field in instance._meta.fields:
field_name = field.name
old_value = getattr(previous, field.name)
new_value = getattr(instance, field.name)
# If the field wasn't modified, no need to check the permissions
if old_value == new_value:
continue
if app_label == 'auth' and model_name == 'user' and field.name == 'password' and request.user.is_anonymous:
# We must ignore password changes from anonymous users since it can be done by people that forgot
# their password. We trust password change form.
continue
if not PermissionBackend.check_perm(request, app_label + ".change_" + model_name + "_" + field_name,
instance):
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raise PermissionDenied(
_("You don't have the permission to change the field {field} on this instance of model"
" {app_label}.{model_name}.")
.format(field=field_name, app_label=app_label, model_name=model_name, )
)
else:
# We check if the user has right to add the object
has_perm = PermissionBackend.check_perm(request, app_label + ".add_" + model_name, instance)
if not has_perm:
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raise PermissionDenied(
_("You don't have the permission to add an instance of model {app_label}.{model_name}.")
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.format(app_label=app_label, model_name=model_name, ))
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def pre_delete_object(instance, **kwargs):
"""
Before a model get deleted, we check the permissions
"""
# noinspection PyProtectedMember
if instance._meta.label_lower in EXCLUDED:
return
if hasattr(instance, "_force_delete") or hasattr(instance, "pk") and instance.pk == 0 \
or hasattr(instance, "_no_signal"):
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# Don't check permissions on force-deleted objects
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return
request = get_current_request()
if request is None:
# Action performed on shell is always granted
return
model_name_full = instance._meta.label_lower.split(".")
app_label = model_name_full[0]
model_name = model_name_full[1]
# We check if the user has rights to delete the object
if not PermissionBackend.check_perm(request, app_label + ".delete_" + model_name, instance):
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raise PermissionDenied(
_("You don't have the permission to delete this instance of model {app_label}.{model_name}.")
.format(app_label=app_label, model_name=model_name))