Fix: authorize document versions by their root and speed up permission id sets (#14396)

* Fix: authorize document versions by their root and speed up permission id sets

permitted_document_ids judged a version by its own owner and grants, so a
version whose owner had drifted from its root's was visible to the wrong
people and hidden from the right ones. Callers patched this individually by
mapping each document to its root first. The query itself was also slow on
MariaDB: the guardian grants were a UNION cast to integers and tested with
IN inside an OR with the owner checks, which MariaDB cannot materialize, so it
re-scans the user's grants for every document. At 20k documents that took
seconds for a user with a couple of hundred grants.

permitted_object_ids now casts the row key to a string, as guardian stores
object_pk, and tests it against a single uncorrelated UNION ALL of the user's
and groups' grants. No integer cast is needed and the user's groups are
matched with an IN subquery rather than a join through the membership table.
Postgres and SQLite build the grant set once, and MariaDB probes guardian's
unique indexes per row, which is cheap. A correlated EXISTS per grant also
fixed MariaDB but was up to 3x slower than before on Postgres and SQLite.

permitted_object_ids also takes an optional parent_field naming a
self-referencing foreign key whose target authorizes the row, and
permitted_document_ids passes root_document, so a version is visible exactly
when its root is. The helper that mapped documents to their roots at the call
sites is no longer needed, so the email, selection data, share link bundle,
trash, bulk download and bulk edit checks use the id set directly.

Co-authored-by: Claude Sonnet 5.5 <noreply@anthropic.com>

src/documents/views.py

@@ -174,7 +174,6 @@ from documents.permissions import TrashPermissions
 from documents.permissions import ViewDocumentsPermissions
 from documents.permissions import annotate_document_count_by_ids
 from documents.permissions import annotate_document_count_for_related_queryset
-from documents.permissions import documents_without_permitted_root
 from documents.permissions import get_document_count_filter_for_user
 from documents.permissions import get_objects_for_user_owner_aware
 from documents.permissions import has_global_statistics_permission
@@ -2117,7 +2116,7 @@ class DocumentViewSet(
         documents = Document.objects.filter(pk__in=document_ids)
         if (
             request.user is not None
-            and documents_without_permitted_root(documents, request.user).exists()
+            and documents.exclude(id__in=permitted_document_ids(request.user)).exists()
         ):
             return HttpResponseForbidden("Insufficient permissions")
 
@@ -3009,12 +3008,8 @@ class DocumentOperationPermissionMixin(PassUserMixin, DocumentSelectionMixin):
             user.has_perm(
                 "documents.change_document",
             )
-            and not Document.global_objects.filter(
-                pk__in=[doc.pk for doc in root_docs],
-            )
-            .exclude(
-                pk__in=permitted_document_ids(user, perm="change_document"),
-            )
+            and not Document.global_objects.filter(pk__in=documents)
+            .exclude(pk__in=permitted_document_ids(user, perm="change_document"))
             .exists()
         )
 
@@ -3627,7 +3622,7 @@ class SelectionDataView(DocumentSelectionMixin, GenericAPIView[Any]):
         documents = Document.objects.filter(pk__in=ids)
         if (
             documents.count() != len(ids)
-            or documents_without_permitted_root(documents, request.user).exists()
+            or documents.exclude(id__in=permitted_document_ids(request.user)).exists()
         ):
             return HttpResponseForbidden("Insufficient permissions")
 
@@ -4124,21 +4119,16 @@ class BulkDownloadView(DocumentSelectionMixin, GenericAPIView[Any]):
             validated_data=serializer.validated_data,
         )
         documents = Document.objects.filter(pk__in=ids)
-        versioned_documents = []
         compression = serializer.validated_data.get("compression")
         content = serializer.validated_data.get("content")
         follow_filename_format = serializer.validated_data.get("follow_formatting")
 
-        permitted_ids = set(permitted_document_ids(request.user))
-        for document in documents:
-            root_doc = get_root_document(document)
-            if root_doc.pk not in permitted_ids:
-                return HttpResponseForbidden("Insufficient permissions")
-            versioned_documents.append(
-                get_latest_version_for_root(
-                    root_doc,
-                ),
-            )
+        if documents.exclude(id__in=permitted_document_ids(request.user)).exists():
+            return HttpResponseForbidden("Insufficient permissions")
+        versioned_documents = [
+            get_latest_version_for_root(get_root_document(document))
+            for document in documents
+        ]
 
         if content == "both":
             strategy_class = OriginalAndArchiveStrategy
@@ -4811,7 +4801,7 @@ class ShareLinkBundleViewSet(PassUserMixin, ModelViewSet[ShareLinkBundle]):
             )
 
         denied_id = (
-            documents_without_permitted_root(documents_qs, request.user)
+            documents_qs.exclude(id__in=permitted_document_ids(request.user))
             .order_by("pk")
             .values_list("pk", flat=True)
             .first()
@@ -5657,11 +5647,12 @@ class TrashView(ListModelMixin, PassUserMixin):
             if doc_ids is not None
             else self.filter_queryset(self.get_queryset()).all()
         )
-        if documents_without_permitted_root(
-            docs,
-            request.user,
-            perm="delete_document",
-            include_deleted=True,
+        if docs.exclude(
+            id__in=permitted_document_ids(
+                request.user,
+                perm="delete_document",
+                include_deleted=True,
+            ),
         ).exists():
             return HttpResponseForbidden("Insufficient permissions")
         action = serializer.validated_data.get("action")