Re: Protect global table from any changes

[Meir Shpilraien <meir@...>]

This is option number 2 I listed. But it will potentially increase memory usage. I would prefer not to allow scripts to create any globals (and somehow force it to make sure scripts can not bypass it).

On Wed, Jan 19, 2022 at 3:39 PM Spar <developspartv@gmail.com> wrote:

How other scripts are run? If you do it from C API you can set environment for each compiled script. On lua side you can use setfenv

On 19 Jan 2022, 16:36 +0300, Meir Shpilraien <meir@redis.com>, wrote:

Hi everyone,

I was wondering what is the recommended way to disallow script changing the global table. The problem I am facing, assuming I provide for example an api to the users, A1, another user can do: 'A1=function ... end', and override my implementation of A1 and cause all other users to run his code.

I can think of multiple ways:
1. Create a lua vm per script - this requires a lot of memory
2. Different environments per script - also might require a lot of memory

3. Make the global table a Readonly tables as described here: http://lua-users.org/wiki/ReadOnlyTables, though in this way user can use rawset to bypass it, and I can not use a userdata to avoid it because I can not set a usedata as a global table (and I do not want to disallow rawset).

Is there any other way to lock the global table from any changes?

I am using lua 5.1.5.

Thanks.

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