Subject: Re: [RFC][PATCH] ns: Syscalls for better namespace sharing control.

From: Daniel Lezcano <[email-masked]>
Date: Thu, 25 Feb 2010 22:31:49 +0100

Eric W. Biederman wrote:
> Introduce two new system calls:
> int nsfd(pid_t pid, unsigned long nstype);
> int setns(unsigned long nstype, int fd);
>
> These two new system calls address three specific problems that can
> make namespaces hard to work with.
> - Namespaces require a dedicated process to pin them in memory.
> - It is not possible to use a namespace unless you are the
>   child of the original creator.
> - Namespaces don't have names that userspace can use to talk
>   about them.
>
> The nsfd() system call returns a file descriptor that can
> be used to talk about a specific namespace, and to keep
> the specified namespace alive.
>
> The fd returned by nsfd() can be bind mounted as:
> mount --bind /proc/self/fd/N /some/filesystem/path
> to keep the namespace alive indefinitely as long as
> it is mounted.
>
> open works on the fd returned by nsfd() so another
> process can get a hold of it and do interesting things.
>
> Overall that allows for persistent naming of namespaces
> according to userspace policy.
>
> setns() allows changing the namespace of the current process
> to a namespace that originates with nsfd().
>
> Signed-off-by: Eric W. Biederman <[email-masked]>
> ---
>   

Is it planned to support all the namespaces for 'nsfd' ?
 I mean will it be possible to specify an Or'ed combination of nstype to 
grab a reference for several namespaces at a time of the targeted process ?

for example : nsfd( 1234, NSTYPE_NET | NSTYPE_IPC, NSTYPE_MNT)