linux-kernel - Re: [RFC PATCH 3/4] kmod - add call_usermodehelper

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Message-ID: <20141125220637.GA10008@redhat.com>
Date:	Tue, 25 Nov 2014 23:06:37 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Ian Kent <ikent@...hat.com>
Cc:	Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"J. Bruce Fields" <bfields@...ldses.org>,
	Stanislav Kinsbursky <skinsbursky@...allels.com>,
	Trond Myklebust <trond.myklebust@...marydata.com>,
	David Howells <dhowells@...hat.com>,
	Benjamin Coddington <bcodding@...hat.com>,
	Al Viro <viro@...IV.linux.org.uk>,
	"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: Re: [RFC PATCH 3/4] kmod - add call_usermodehelper_ns() helper

On 11/25, Oleg Nesterov wrote:
>
> Let me first apologize, I didn't actually read this series yet.
>
> But I have to admit that so far I do not like this approach...
> probably I am biased.

Yes.

And I have another concern... this is mostly a feeling, I can be
easily wrong but:

> On 11/25, Ian Kent wrote:
> >
> > +static int umh_set_ns(struct subprocess_info *info, struct cred *new)
> > +{
> > +	struct nsproxy *ns = info->data;
> > +
> > +	mntns_setfs(ns->mnt_ns);
>
> Firstly, it is not clear to me if we should use the caller's ->mnt_ns.
> Let me remind about the coredump. The dumping task can cloned with
> CLONE_NEWNS or it cam do unshare(NEWNS)... but OK, I do not understand
> this enough.

And otoh. If we actually want to use the caller's mnt_ns/namespaces we
could simply fork/reparent a child which will do execve ?

Oleg.

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