Re: RFC: on adding new CLONE_* flags [WAS Re: [PATCH 0/4] clone: add CLONE_PIDFD]

[Florian Weimer <fweimer@redhat.com>]

* Andy Lutomirski:

> I would personally *love* it if distros started setting no_new_privs
> for basically all processes.

Wouldn't no_new_privs inhibit all security transitions, including those
that reduce privileges?  And therefore effectively reduce security?

> Anyway, clone(2) is an enormous mess.  Surely the right solution here
> is to have a whole new process creation API that takes a big,
> extensible struct as an argument, and supports *at least* the full
> abilities of posix_spawn() and ideally covers all the use cases for
> fork() + do stuff + exec().  It would be nifty if this API also had a
> way to say "add no_new_privs and therefore enable extra functionality
> that doesn't work without no_new_privs".  This functionality would
> include things like returning a future extra-privileged pidfd that
> gives ptrace-like access.

I agree that consistent replacement for the clone system call makes
sense.  I'm not sure if covering everything that posix_spawn could do
would make sense.  There seems to be some demand to be able to do large
parts of container setup using posix_spawn, so we'll probably add
support for things like writing to arbitrary files eventually.  And of
course, proper error reporting, so that you can figure out which file
creation action failed.

Thanks,
Florian