[tarantool-patches] Re: [PATCH] Make access_check_ddl check for entity privileges.

From: Sergey Petrenko <sergepetrenko@xxxxxxxxxxxxx>
To: tarantool-patches@xxxxxxxxxxxxx
Date: Thu, 19 Jul 2018 10:48:45 +0300

Sorry, forgot to send to the mailing list.

-------- Перенаправленное сообщение --------
Тема: Re: [tarantool-patches] Re: [PATCH] Make access_check_ddl check for entity privileges.
Дата:   Thu, 19 Jul 2018 10:46:27 +0300
От:     Sergey Petrenko <sergepetrenko@xxxxxxxxxxxxx>
Кому:   Konstantin Osipov <kostja@xxxxxxxxxxxxx>

18.07.2018 9:07, Konstantin Osipov пишет:

* Sergey Petrenko <sergepetrenko@xxxxxxxxxxxxx> [18/07/12 11:55]:

-       enum priv_type priv_type = new_tuple ? PRIV_C : PRIV_D;
-       if (old_tuple && new_tuple)
-               priv_type = PRIV_A;
-       access_check_ddl(old_space->def->name, old_space->def->uid, SC_SPACE,
-                        priv_type, true);
+       enum priv_type priv_type = new_tuple ? PRIV_A : PRIV_D;
+       access_check_ddl(old_space->def->name, old_space->def->id,
+                        old_space->def->uid, SC_SPACE, priv_type, true);

As far as I understand, you changed it because creating an index
is technically altering a space, not creating it. But in this case
dropping an index is also technically altering a space.
In SQL, CREATE/DROP/ALTER match SQL statements CREATE/DROP/ALTER
respectively. Since in NoSQL in Tarantool we don't have these
statements, instead, we create each index with a separate Lua
command, let's keep the old check: use CREATE access to space
in order to permit CREATING an index, ALTER - to permit update,
and DROP - to permit drop.

Checking for create privilege ignores ownership, since when creating an
object there can't be a create privilege on the object itself.

INDEX is not a separate object, it's a part of the space.
A user who has created the space should be able to
CREATE/DROP/ALTER any index in the space based on the definer
rule (the owner of the object should be able to do anything with
it).

You misunderstood me, I meant the space object, since we used to
check for CREATE privilege on space itself to create an index previously.
Checking for ALTER on space, would allow exactly what you want with
CREATE/ALTER/DROP of an index. The owner has every privilege, including
ALTER, so he is able to do anything with the indices.
If someone else created an index on your space, and you want to drop it,
it is no problem. This is why we check for ALTER OR DROP on space in case
of dropping an index.

I imagine if an index has an independent owner, one would not be
able to drop their own space if some other user created an index
on it.

Let's try to avoid this. Oracle also has entity access. How does
it work there? Who is set as the definer of the index if user b
creates an index on space created by user a? Let's bring this up
with Peter Gulutzan, he may have an educated opinion on the
subject.

What Oracle does is they have separate entities INDEX and TABLE,
and in order to create an index, you need to have an INDEX privilege
on a space OR you may have a CREATE ANY INDEX privilege.
So, technically, non-owners can create indices in your
tables, but again, if you want to drop a table, it is dropped together
with all the indices no matter who their owner is. (The same thing we
may achieve with privilege checks that I and Georgy propose).

We also have an option of separating INDEX and SPACE as entities,
and introducing INDEX entity. But then again a user who created a
space should be able to create/drop/alter any index in that space
- the opposite seems counter-intuitive.

IMO it would unnecessarily complicate access control, cos we would
need to grant all the needed privileges on an index to space owner,
and we also would have to make it so that theese privileges cannot be
revoked.
OR we can set space owner as the definer of any index created on that space,
but again, this seems strange. If you are a non-owner of the space,
you create an index and immediately lose control over it.

We may also consult with Peter Gulutzan. Do you want me to write him?

[tarantool-patches] Re: [PATCH] Make access_check_ddl check for entity privileges.

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