Re: [PATCH] tmpfs: verify {g,u}id mount options correctly

Christian Brauner
2023-08-07T08:56:13Z

On Tue, 01 Aug 2023 18:17:04 +0200, Christian Brauner wrote:
> A while ago we received the following report:
>
> "The other outstanding issue I noticed comes from the fact that
> fsconfig syscalls may occur in a different userns than that which
> called fsopen. That means that resolving the uid/gid via
> current_user_ns() can save a kuid that isn't mapped in the associated
> namespace when the filesystem is finally mounted. This means that it
> is possible for an unprivileged user to create files owned by any
> group in a tmpfs mount (since we can set the SUID bit on the tmpfs
> directory), or a tmpfs that is owned by any user, including the root
> group/user."
>
> [...]

Applied to the vfs.tmpfs branch of the vfs/vfs.git tree.
Patches in the vfs.tmpfs branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs.tmpfs

[1/1] tmpfs: verify {g,u}id mount options correctly