Messages in this thread | | | From | (Eric W. Biederman) | Date | Mon, 12 Nov 2012 18:37:33 -0800 | Subject | Re: [PATCH] userns: Support fuse interacting with multiple user namespaces |
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Miklos Szeredi <miklos@szeredi.hu> writes:
> ebiederm@xmission.com (Eric W. Biederman) writes: > >> Use kuid_t and kgid_t in struct fuse_conn and struct fuse_mount_data. >> >> The connection between between a fuse filesystem and a fuse daemon is >> established when a fuse filesystem is mounted and provided with a file >> descriptor the fuse daemon created by opening /dev/fuse. >> >> For now restrict the communication of uids and gids between the fuse >> filesystem and the fuse daemon to the initial user namespace. > > Why? > > I think far more logical would be to limit a single instance of the > filesystem and the daemon to an arbitrary but *single* namespace. > I.e. one fuse_conn <-> one user namespace. > > Is there a reason to treat the initial namespace specially?
Stepwise making this work.
The initial user namespace is special in that is the only user namespace you can currently mount a filesystem in.
My goal with the posted patch is to support users on the other side of the vfs that are in multiple user namespaces. Which basically means accepting kuid_t and kgid_t values and converting them to uid_t and gid_t values where needed.
As for creating a version of fuse that can be mounted in different user namespaces and can communicate with the fuse daemon in the user namespace the filesystem was mounted in, I have a preliminary patch for that. My goal with that patch is to support unprivileged mounts of fuse without the help of a suid root mount program. But that patch is more involved and not quite ready yet.
I want to get to the point that I can enable fuse and user namespaces at the same time (what this patch allows) and then put in the effort to fully take advantage of user namespaces.
Eric
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