On 2019-04-15, Enrico Weigelt, metux IT consult <lkml@metux.net> wrote:
> > This patchset makes it possible to retrieve pid file descriptors at
> > process creation time by introducing the new flag CLONE_PIDFD to the
> > clone() system call as previously discussed.
> 
> Sorry, for highjacking this thread, but I'm curious on what things to
> consider when introducing new CLONE_* flags.
> 
> The reason I'm asking is:
> 
> I'm working on implementing plan9-like fs namespaces, where unprivileged
> processes can change their own namespace at will. For that, certain
> traditional unix'ish things have to be disabled, most notably suid.
> As forbidding suid can be helpful in other scenarios, too, I thought
> about making this its own feature. Doing that switch on clone() seems
> a nice place for that, IMHO.

Just spit-balling -- is no_new_privs not sufficient for this usecase?
Not granting privileges such as setuid during execve(2) is the main
point of that flag.

-- 
Aleksa Sarai
Senior Software Engineer (Containers)
SUSE Linux GmbH
<https://www.cyphar.com/>