Re: [RFC PATCH 0/4] namespacefs: Proof-of-Concept

[Yordan Karadzhov]

On 22.11.21 г. 17:47 ч., James Bottomley wrote:
> > Hmm, Isn't that true only if somehow we know that (3) happened before
> > (4).
> This depends.  There are only two parented namespaces: pid and user.
> You said you were only interested in pid for now.  setns on the process
> only affects pid_for_children because you have to fork to enter the pid
> namespace, so in your scenario X has a new ns/pid_for_children but its
> own ns/pid never changed.  It's the ns/pid not the ns/pid_for_children
> which is the parent.  This makes me suspect that the specific thing
> you're trying to do: trace the pid parentage, can actually be done with
> the information we have now.

This is very good point indeed. Thank you very much!
Yordan

> If you do this with the user_ns, then you have a problem because it's
> not fork on entry.  But, as I listed in the examples, there are a load
> of other problems with tracing the user_ns tree.