Re: [PATCH v3 00/25] user_namespace: introduce fsid mappings
From: Serge E. Hallyn
Date: Wed Feb 19 2020 - 14:36:02 EST
On Tue, Feb 18, 2020 at 03:33:46PM +0100, Christian Brauner wrote:
> With fsid mappings we can solve this by writing an id mapping of 0
> 100000 100000 and an fsid mapping of 0 300000 100000. On filesystem
> access the kernel will now lookup the mapping for 300000 in the fsid
> mapping tables of the user namespace. And since such a mapping exists,
> the corresponding files will have correct ownership.
So if I have
/proc/self/uid_map: 0 100000 100000
/proc/self/fsid_map: 1000 1000 1
1. If I read files from the rootfs which have host uid 101000, they
will appear as uid 100 to me?
2. If I read host files with uid 1000, they will appear as uid 1000 to me?
3. If I create a new file, as uid 1000, what will be the inode owning uid?