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/tests/test_permission_filtering_security.py

@@ -32,6 +32,8 @@ from paperless_testing.permissions import grant_global
 from paperless_testing.permissions import grant_object
 
 if TYPE_CHECKING:
+    from django.contrib.auth.models import User
+
     from paperless_testing.dirs import PaperlessDirs
 
 
@@ -178,6 +180,296 @@ class TestPermittedDocumentIdsIncludeDeleted:
         )
 
 
+@pytest.mark.django_db
+class TestPermittedDocumentIdsVersions:
+    """
+    A version is authorized by its root document: the version's own owner and
+    grants never matter.
+    """
+
+    @pytest.mark.parametrize(
+        ("root_owner", "version_owner", "expected_visible"),
+        [
+            pytest.param(
+                "other",
+                "nobody",
+                False,
+                id="unowned-version-of-private-root",
+            ),
+            pytest.param("other", "user", False, id="own-version-of-private-root"),
+            pytest.param("user", "other", True, id="foreign-version-of-own-root"),
+            pytest.param("user", "nobody", True, id="unowned-version-of-own-root"),
+            pytest.param("nobody", "other", True, id="private-version-of-unowned-root"),
+        ],
+    )
+    def test_version_follows_root_owner(
+        self,
+        root_owner: str,
+        version_owner: str,
+        *,
+        expected_visible: bool,
+    ) -> None:
+        """
+        GIVEN:
+            - A root document and a version with differing owners
+        WHEN:
+            - The permitted document ids are resolved for the user
+        THEN:
+            - The version is visible exactly when its root is
+        """
+        user = UserFactory()
+        owners = {"user": user, "other": UserFactory(), "nobody": None}
+        root = DocumentFactory(owner=owners[root_owner])
+        version = DocumentFactory(root_document=root, owner=owners[version_owner])
+
+        visible = set(permitted_document_ids(user))
+
+        assert (version.pk in visible) is expected_visible
+        assert (root.pk in visible) is expected_visible
+
+    @staticmethod
+    def grantee(user: User, kind: str) -> User | Group:
+        """The user itself, or a new group the user belongs to."""
+        if kind == "user":
+            return user
+        group = Group.objects.create(name="shared")
+        user.groups.add(group)
+        return group
+
+    @pytest.mark.parametrize(
+        "grantee_kind",
+        [pytest.param("user", id="user"), pytest.param("group", id="group")],
+    )
+    def test_grant_on_root_applies_to_version(self, grantee_kind: str) -> None:
+        """
+        GIVEN:
+            - A private root document shared with a user or one of their groups
+            - A version of it owned by someone else
+        WHEN:
+            - The permitted document ids are resolved for the user
+        THEN:
+            - Both the root and the version are visible
+            - A user without the grant sees neither
+        """
+        user = UserFactory()
+        stranger = UserFactory()
+        root = DocumentFactory(owner=UserFactory())
+        version = DocumentFactory(root_document=root, owner=UserFactory())
+        grant_object(self.grantee(user, grantee_kind), root, "view_document")
+
+        assert_visible_document_ids(
+            permitted_document_ids(user),
+            expected_visible=[root.pk, version.pk],
+            expected_hidden=[],
+        )
+        assert_visible_document_ids(
+            permitted_document_ids(stranger),
+            expected_visible=[],
+            expected_hidden=[root.pk, version.pk],
+        )
+
+    @pytest.mark.parametrize(
+        "grantee_kind",
+        [pytest.param("user", id="user"), pytest.param("group", id="group")],
+    )
+    def test_grant_on_version_is_ignored(self, grantee_kind: str) -> None:
+        """
+        GIVEN:
+            - A private root document
+            - A version with an explicit grant for the user or one of their groups
+        WHEN:
+            - The permitted document ids are resolved for the user
+        THEN:
+            - Neither the root nor the version is visible
+        """
+        user = UserFactory()
+        root = DocumentFactory(owner=UserFactory())
+        version = DocumentFactory(root_document=root, owner=UserFactory())
+        grant_object(self.grantee(user, grantee_kind), version, "view_document")
+
+        assert_visible_document_ids(
+            permitted_document_ids(user),
+            expected_visible=[],
+            expected_hidden=[root.pk, version.pk],
+        )
+
+    def test_grant_on_one_root_does_not_reach_another_roots_version(self) -> None:
+        """
+        GIVEN:
+            - Two private roots, each with a version
+            - The user may view only the first root
+        WHEN:
+            - The permitted document ids are resolved for the user
+        THEN:
+            - Only the first root and its version are visible
+        """
+        user = UserFactory()
+        first = DocumentFactory(owner=UserFactory())
+        first_version = DocumentFactory(root_document=first, owner=UserFactory())
+        second = DocumentFactory(owner=UserFactory())
+        second_version = DocumentFactory(root_document=second, owner=user)
+        grant_object(user, first, "view_document")
+
+        assert_visible_document_ids(
+            permitted_document_ids(user),
+            expected_visible=[first.pk, first_version.pk],
+            expected_hidden=[second.pk, second_version.pk],
+        )
+
+    def test_user_in_several_groups(self) -> None:
+        """
+        GIVEN:
+            - A user in two groups
+            - Two private roots shared with one group each, and a third shared with nobody
+            - A version of each root
+        WHEN:
+            - The permitted document ids are resolved for the user
+        THEN:
+            - The two shared roots and their versions are visible
+            - The third root and its version are not
+        """
+        user = UserFactory()
+        groups = [Group.objects.create(name=f"group{i}") for i in range(2)]
+        user.groups.add(*groups)
+        shared = [DocumentFactory(owner=UserFactory()) for _ in groups]
+        for root, group in zip(shared, groups, strict=True):
+            grant_object(group, root, "view_document")
+        unshared = DocumentFactory(owner=UserFactory())
+        shared_versions = [
+            DocumentFactory(root_document=root, owner=UserFactory()) for root in shared
+        ]
+        unshared_version = DocumentFactory(root_document=unshared, owner=None)
+
+        assert_visible_document_ids(
+            permitted_document_ids(user),
+            expected_visible=[
+                *(root.pk for root in shared),
+                *(version.pk for version in shared_versions),
+            ],
+            expected_hidden=[unshared.pk, unshared_version.pk],
+        )
+
+    def test_permission_is_resolved_through_the_root(self) -> None:
+        """
+        GIVEN:
+            - A private root document where the user may view and change
+        WHEN:
+            - The permitted ids are resolved for view, change and delete
+        THEN:
+            - The version is visible for view and change only
+        """
+        user = UserFactory()
+        root = DocumentFactory(owner=UserFactory())
+        version = DocumentFactory(root_document=root, owner=UserFactory())
+        grant_object(user, root, "view_document", "change_document")
+
+        assert version.pk in set(permitted_document_ids(user))
+        assert version.pk in set(permitted_document_ids(user, perm="change_document"))
+        assert version.pk in set(
+            permitted_document_ids(user, perm="documents.change_document"),
+        )
+        assert version.pk not in set(
+            permitted_document_ids(user, perm="delete_document"),
+        )
+
+    def test_anonymous_sees_versions_of_unowned_roots_only(self) -> None:
+        """
+        GIVEN:
+            - A version owned by nobody under a private root
+            - A version owned by someone under an unowned root
+        WHEN:
+            - The permitted document ids are resolved for an anonymous user
+        THEN:
+            - Only the version of the unowned root is visible
+        """
+        private_root = DocumentFactory(owner=UserFactory())
+        private_version = DocumentFactory(root_document=private_root, owner=None)
+        open_root = DocumentFactory(owner=None)
+        open_version = DocumentFactory(root_document=open_root, owner=UserFactory())
+
+        assert_visible_document_ids(
+            permitted_document_ids(AnonymousUser()),
+            expected_visible=[open_root.pk, open_version.pk],
+            expected_hidden=[private_root.pk, private_version.pk],
+        )
+
+    def test_deleted_versions_follow_their_deleted_root(self) -> None:
+        """
+        GIVEN:
+            - A soft-deleted root document and its version, which deleting the
+              root soft-deletes too; the version is owned by someone else
+        WHEN:
+            - The permitted document ids are resolved with and without deleted
+              documents
+        THEN:
+            - Nothing is visible by default
+            - With deleted documents included, the version is visible to the
+              root's owner and not to the version's own owner
+        """
+        owner = UserFactory()
+        version_owner = UserFactory()
+        root = DocumentFactory(owner=owner)
+        version = DocumentFactory(root_document=root, owner=version_owner)
+        root.delete()
+
+        assert not {root.pk, version.pk} & set(permitted_document_ids(owner))
+        assert_visible_document_ids(
+            permitted_document_ids(owner, include_deleted=True),
+            expected_visible=[root.pk, version.pk],
+            expected_hidden=[],
+        )
+        assert_visible_document_ids(
+            permitted_document_ids(version_owner, include_deleted=True),
+            expected_visible=[],
+            expected_hidden=[root.pk, version.pk],
+        )
+
+    @pytest.mark.parametrize(
+        "is_superuser",
+        [
+            pytest.param(False, id="regular-user"),
+            pytest.param(True, id="superuser"),
+        ],
+    )
+    def test_inactive_user_sees_no_versions(self, *, is_superuser: bool) -> None:
+        """
+        GIVEN:
+            - An inactive user, possibly a superuser, who owns a root and its version
+        WHEN:
+            - The permitted document ids are resolved for them
+        THEN:
+            - Nothing is visible
+        """
+        user = UserFactory(is_active=False, is_superuser=is_superuser)
+        root = DocumentFactory(owner=user)
+        version = DocumentFactory(root_document=root, owner=user)
+
+        assert_visible_document_ids(
+            permitted_document_ids(user),
+            expected_visible=[],
+            expected_hidden=[root.pk, version.pk],
+        )
+
+    def test_superuser_sees_all_versions(self) -> None:
+        """
+        GIVEN:
+            - A private root owned by someone else, with a version
+        WHEN:
+            - The permitted document ids are resolved for a superuser
+        THEN:
+            - Both the root and the version are visible
+        """
+        superuser = UserFactory(superuser=True)
+        root = DocumentFactory(owner=UserFactory())
+        version = DocumentFactory(root_document=root, owner=UserFactory())
+
+        assert_visible_document_ids(
+            permitted_document_ids(superuser),
+            expected_visible=[root.pk, version.pk],
+            expected_hidden=[],
+        )
+
+
 @pytest.mark.django_db
 class TestAiChatAllDocumentsPermissionBoundary:
     """