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				https://gitlab.crans.org/bde/nk20
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			240 lines
		
	
	
		
			8.7 KiB
		
	
	
	
		
			Python
		
	
	
	
	
	
			
		
		
	
	
			240 lines
		
	
	
		
			8.7 KiB
		
	
	
	
		
			Python
		
	
	
	
	
	
# Copyright (C) 2018-2025 by BDE ENS Paris-Saclay
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# SPDX-License-Identifier: GPL-3.0-or-later
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from datetime import date, timedelta
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from django.contrib.auth.backends import ModelBackend
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from django.contrib.auth.models import User
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from django.contrib.contenttypes.models import ContentType
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from django.db.models import Q, F
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from django.utils import timezone
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from note.models import Note, NoteUser, NoteClub, NoteSpecial
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from note_kfet.middlewares import get_current_request
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from member.models import Membership, Club
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from .decorators import memoize
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from .models import Permission
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class PermissionBackend(ModelBackend):
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    """
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    Manage permissions of users
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    """
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    supports_object_permissions = True
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    supports_anonymous_user = False
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    supports_inactive_user = False
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    @staticmethod
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    @memoize
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    def get_raw_permissions(request, t):
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        """
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        Query permissions of a certain type for a user, then memoize it.
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        :param request: The current request
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        :param t: The type of the permissions: view, change, add or delete
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        :return: The queryset of the permissions of the user (memoized) grouped by clubs
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        """
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        if hasattr(request, 'auth') and request.auth is not None and hasattr(request.auth, 'scope'):
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            # OAuth2 Authentication
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            user = request.auth.user
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            def permission_filter(membership_obj):
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                query = Q(pk=-1)
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                for scope in request.auth.scope.split(' '):
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                    permission_id, club_id = scope.split('_')
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                    if int(club_id) == membership_obj.club_id:
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                        query |= Q(pk=permission_id)
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                return query
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        else:
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            user = request.user
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            def permission_filter(membership_obj):
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                return Q(mask__rank__lte=request.session.get("permission_mask", 42))
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        if user.is_anonymous:
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            # Unauthenticated users have no permissions
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            return Permission.objects.none()
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        memberships = Membership.objects.filter(user=user).all()
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        perms = []
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        for membership in memberships:
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            for role in membership.roles.all():
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                for perm in role.permissions.filter(permission_filter(membership), type=t).all():
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                    if not perm.permanent:
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                        if membership.date_start > date.today() or membership.date_end < date.today():
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                            continue
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                    perm.membership = membership
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                    perms.append(perm)
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        return perms
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    @staticmethod
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    def permissions(request, model, type):
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        """
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        List all permissions of the given user that applies to a given model and a give type
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        :param request: The current request
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        :param model: The model that the permissions shoud apply
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        :param type: The type of the permissions: view, change, add or delete
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        :return: A generator of the requested permissions
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        """
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        if hasattr(request, 'auth') and request.auth is not None and hasattr(request.auth, 'scope'):
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            # OAuth2 Authentication
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            user = request.auth.user
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        else:
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            user = request.user
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        for permission in PermissionBackend.get_raw_permissions(request, type):
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            if not isinstance(model.model_class()(), permission.model.model_class()) or not permission.membership:
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                continue
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            membership = permission.membership
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            club = membership.club
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            permission = permission.about(
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                user=user,
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                club=club,
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                membership=membership,
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                User=User,
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                Club=Club,
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                Membership=Membership,
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                Note=Note,
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                NoteUser=NoteUser,
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                NoteClub=NoteClub,
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                NoteSpecial=NoteSpecial,
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                F=F,
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                Q=Q,
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                now=timezone.now(),
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                today=date.today(),
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                week=timedelta(days=7),
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            )
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            yield permission
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    @staticmethod
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    @memoize
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    def filter_queryset(request, model, t, field=None):
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        """
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        Filter a queryset by considering the permissions of a given user.
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        :param request: The current request
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        :param model: The concerned model of the queryset
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        :param t: The type of modification (view, add, change, delete)
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        :param field: The field of the model to test, if concerned
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        :return: A query that corresponds to the filter to give to a queryset
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        """
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        if hasattr(request, 'auth') and request.auth is not None and hasattr(request.auth, 'scope'):
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            # OAuth2 Authentication
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            user = request.auth.user
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        else:
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            user = request.user
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        if user is None or user.is_anonymous:
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            # Anonymous users can't do anything
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            return Q(pk=-1)
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        if user.is_superuser and request.session.get("permission_mask", -1) >= 42:
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            # Superusers have all rights
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            return Q()
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        if not isinstance(model, ContentType):
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            model = ContentType.objects.get_for_model(model)
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        # Never satisfied
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        query = Q(pk=-1)
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        perms = PermissionBackend.permissions(request, model, t)
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        for perm in perms:
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            if perm.field and field != perm.field:
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                continue
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            if perm.type != t or perm.model != model:
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                continue
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            perm.update_query()
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            query = query | perm.query
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        return query
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    @staticmethod
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    @memoize
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    def check_perm(request, perm, obj=None):
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        """
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        Check is the given user has the permission over a given object.
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        The result is then memoized.
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        Exception: for add permissions, since the object is not hashable since it doesn't have any
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        primary key, the result is not memoized. Moreover, the right could change
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        (e.g. for a transaction, the balance of the user could change)
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        """
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        # Requested by a shell
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        if request is None:
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            return False
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        user_obj = request.user
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        sess = request.session
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        if hasattr(request, 'auth') and request.auth is not None and hasattr(request.auth, 'scope'):
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            # OAuth2 Authentication
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            user_obj = request.auth.user
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        if user_obj is None or user_obj.is_anonymous:
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            return False
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        if user_obj.is_superuser and sess.get("permission_mask", -1) >= 42:
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            return True
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        if obj is None:
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            return True
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        perm = perm.split('.')[-1].split('_', 2)
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        perm_type = perm[0]
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        perm_field = perm[2] if len(perm) == 3 else None
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        ct = ContentType.objects.get_for_model(obj)
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        if any(permission.applies(obj, perm_type, perm_field)
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               for permission in PermissionBackend.permissions(request, ct, perm_type)):
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            return True
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        return False
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    def has_perm(self, user_obj, perm, obj=None):
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        # Warning: this does not check that user_obj has the permission,
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        # but if the current request has the permission.
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        # This function is implemented for backward compatibility, and should not be used.
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        return PermissionBackend.check_perm(get_current_request(), perm, obj)
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    def has_module_perms(self, user_obj, app_label):
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        return False
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    @staticmethod
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    @memoize
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    def has_model_perm(request, model, type):
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        """
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        Check is the given user has the permission over a given model for a given action.
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        The result is then memoized.
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        :param request: The current request
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        :param model: The model that the permissions shoud apply
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        :param type: The type of the permissions: view, change, add or delete
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        For view action, it is consider possible if user can view or change the model
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        """
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        # Requested by a shell
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        if request is None:
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            return False
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        user_obj = request.user
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        sess = request.session
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        if hasattr(request, 'auth') and request.auth is not None and hasattr(request.auth, 'scope'):
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            # OAuth2 Authentication
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            user_obj = request.auth.user
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        if user_obj is None or user_obj.is_anonymous:
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            return False
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        if user_obj.is_superuser and sess.get("permission_mask", -1) >= 42:
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            return True
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        ct = ContentType.objects.get_for_model(model)
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        if any(PermissionBackend.permissions(request, ct, type)):
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            return True
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        if type == "view" and any(PermissionBackend.permissions(request, ct, "change")):
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            return True
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        return False
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    def get_all_permissions(self, user_obj, obj=None):
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        ct = ContentType.objects.get_for_model(obj)
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        return list(self.permissions(get_current_request(), ct, "view"))
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