Messages in this thread | | | Subject | Re: [RFC PATCH 3/8] kmod - teach call_usermodehelper() to use a namespace | From | Ian Kent <> | Date | Mon, 16 Feb 2015 14:16:57 +0800 |
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On Tue, 2015-02-10 at 17:55 +0100, Oleg Nesterov wrote: > On 02/10, Ian Kent wrote: > > > > On Mon, 2015-02-09 at 17:03 +0100, Oleg Nesterov wrote: > > > > > > I understand. but I still can't understand why we can't implement something > > > like > > > enter_ns(struct nsproxy *p) > > > { > > > new_nsproxy = create_new_namespaces(...); > > > > > > p->mnt_ns->ns->ops->install(new_nsproxy, ...); > > > p->pid_ns_for_children->ns->ops->install(new_nsproxy, ...); > > > ... > > > > > > switch_task_namespaces(new_nsproxy); > > > } > > > > > > Why we should abuse fs/proc ? > > > > That sounds like a much better approach. > > Your saying just take a reference to the nsproxy from the located > > process and use it instead, right? > > Yes,
I'm still not sure if this can be done (at least without surgery to the namespace implementation) and I think I've been here before which is what lead to the file_open_root() approach.
The difficulty is the second parameter to the install() call above, the struct ns_common. In setns() it's obtained from the procfs file inode and the file open is what's used to obtain each namespace type (in the form of a struct ns_common) from a process context different from current, current being the thread runner process.
I might still be able to work out a (viable) way to obtain the appropriate ns_common struct in each case without a file open but it's hard to see how.
Ian
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