Re: [PATCH v2 10/10] Allow --userns when pasta spawns a command

[David Gibson <david@gibson.dropbear.id.au>]

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On Fri, Sep 09, 2022 at 04:34:25PM +0200, Stefano Brivio wrote:
> On Thu,  8 Sep 2022 13:59:07 +1000
> David Gibson <david(a)gibson.dropbear.id.au> wrote:
> 
> > Currently --userns is only allowed when pasta is attaching to an existing
> > netns or PID, and is prohibited when creating a new netns by spawning a
> > command or shell.
> > 
> > With the new handling of userns, this check isn't neccessary.  I'm not sure
> > if there's any use case for --userns with a spawned command, but it's
> > strictly more flexible and requires zero extra code, so we might as well.
> 
> I think it's helpful because one might not be able to join a network
> namespace without first joining a given user namespace.

Well.. this is strictly for the spawning command case, so we're
creating the network ns rather than joining one.

> So, if you want to run any network-ish command in such a network
> namespace, using pasta instead of nsenter for whatever reason, this
> possibility might be practical.
> 
> > Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
> > ---
> >  conf.c | 5 -----
> >  1 file changed, 5 deletions(-)
> > 
> > diff --git a/conf.c b/conf.c
> > index 27d520e..ec191c2 100644
> > --- a/conf.c
> > +++ b/conf.c
> > @@ -561,11 +561,6 @@ static int conf_pasta_ns(int *netns_only, char *userns, char *netns,
> >  		}
> >  	}
> >  
> > -	if (*userns && !*netns) {
> > -		err("--userns requires --netns or PID");
> > -		return -EINVAL;
> > -	}
> 
> I guess we should now drop this sentence about --userns from the man
> page:
> 
>   This option requires --netns or a PID to be specified.
> 
> ...either drop it, or clarify that a command might also be given
> instead, I'm not sure.

Good point, I'll adjust.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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