linux-kernel - Re: [GIT PULL] userns related vfs enhancements for v4.8

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Date:	Tue, 26 Jul 2016 19:02:24 -0500
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Michał Zegan <webczat_200@...zta.onet.pl>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Containers <containers@...ts.linux-foundation.org>,
	linux-fsdevel@...r.kernel.org,
	Seth Forshee <seth.forshee@...onical.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [GIT PULL] userns related vfs enhancements for v4.8

Michał Zegan <webczat_200@...zta.onet.pl> writes:

> I have one question: what uids are written in the filesystem inodes?
> those that the kernel sees, or those mapped by user namespaces? and so,
> is it true that the filesystem will still require shifting uids,
> directly or indirectly, to be usable from inside user namespace? can't
> uids be mapped dynamically from what is in the inode to kernel uids
> based on the user namespace they are used from? Maybe because the fs can
> be mounted from outside before starting the container?

Feel free to read the code.  As best I can understand your question the
best answer is in reading and understanding the code yourself.

Eric