Security modules and sending signals within the same process

[Florian Weimer]

* Stephen Smalley:

> Looks like commit 065add3941bd ("signals: check_kill_permission():
> don't check creds if same_thread_group()") skipped the uid-based
> checks if the sender and target were in the same thread group, but not
> the security hook call.  One could argue that the security hook call
> ought to be skipped in that case as well using the same rationale
> given in that commit.  Nothing appears to guarantee the property you
> state above for security_task_kill implementations, although none of
> the in-tree users are based on uids or gids so setresuid/setresgid
> shouldn't affect them.

Okay, thanks, so it looks like I don't have to do anything special to
support thread cancellation.

Florian