linux-kernel - Re: [PATCH RESEND v2 00/19] Support fuse mounts in user namespaces

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Date:	Mon, 25 Jan 2016 13:47:22 -0600
From:	Seth Forshee <seth.forshee@...onical.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	linux-bcache@...r.kernel.org, dm-devel@...hat.com,
	linux-raid@...r.kernel.org, linux-mtd@...ts.infradead.org,
	linux-fsdevel@...r.kernel.org, fuse-devel@...ts.sourceforge.net,
	linux-security-module@...r.kernel.org, selinux@...ho.nsa.gov
Cc:	Alexander Viro <viro@...iv.linux.org.uk>,
	Serge Hallyn <serge.hallyn@...onical.com>,
	Richard Weinberger <richard.weinberger@...il.com>,
	Austin S Hemmelgarn <ahferroin7@...il.com>,
	Miklos Szeredi <miklos@...redi.hu>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND v2 00/19] Support fuse mounts in user namespaces

On Mon, Jan 04, 2016 at 12:03:39PM -0600, Seth Forshee wrote:
> These patches implement support for mounting filesystems in user
> namespaces using fuse. They are based on the patches in the for-testing
> branch of
> git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git,
> but I've rebased them onto 4.4-rc3. I've pushed all of this to:
> 
>  git://git.kernel.org/pub/scm/linux/kernel/git/sforshee/linux.git fuse-userns
> 
> The patches are organized into three high-level groups.
> 
> Patches 1-6 are related to security, adding restrictions for
> unprivileged mounts and updating the LSMs as needed. Patches 1-2
> (checking inode permissions for block device mounts) may not be strictly
> necessary for fuseblk mounts since fuse doesn't do any IO on the block
> device in the kernel, but it still seems like a good idea to fail the
> mount if the user doesn't have the required permissions for the inode
> (though this is a bit misleading with fuse since the mounts are done via
> a suid-root helper).
> 
> Patches 7-14 update most of the vfs to translate ids correctly and deal
> with inodes which may have invalid user/group ids. I've omitted patches
> for anything not used by fuse - quota, fs freezing, some helper
> functions, etc. - but if these are wanted for the sake of completeness I
> can include them.
> 
> Patches 15-18 update fuse to deal with mounts from non-init pid and user
> namespaces and enable mounting from user namespaces.
> 
> Changes since v1:
>  - Drop patch for FIBMAP.
>  - Use current_in_userns in fuse_allow_current_process.
>  - Remove checks for uid/gid validity in fuse. Intead, ids from the
>    backing store which do not map into s_user_ns will result in invalid
>    ids in the vfs inode. Checks in the vfs will prevent unmappable ids
>    from being passed in from above.
>  - Update a couple of commit messages to provide more detail about
>    changes.

Now that the merge window is over, I'm wondering whether it might be
possible to get some feedback on these patches this cycle?

Thanks,
Seth