Re: [RFC PATCH v1 0/5] Add support for O_MAYEXEC

From: James Morris
Date: Wed Dec 12 2018 - 14:52:20 EST

On Wed, 12 Dec 2018, Mickaël Salaün wrote:

> Hi,
> The goal of this patch series is to control script interpretation. A
> new O_MAYEXEC flag used by sys_open() is added to enable userland script
> interpreter to delegate to the kernel (and thus the system security
> policy) the permission to interpret scripts or other files containing
> what can be seen as commands.
> The security policy is the responsibility of an LSM. A basic
> system-wide policy is implemented with Yama and configurable through a
> sysctl.

If you're depending on the script interpreter to flag that the user may
execute code, this seems to be equivalent in security terms to depending
on the user. e.g. what if the user uses ptrace and clears O_MAYEXEC?

James Morris