Pull vfs overlayfs updates from Christian Brauner:
"Currently overlayfs uses the mounter's credentials for its
override_creds() calls. That provides a consistent permission model.
This patches allows a caller to instruct overlayfs to use its
credentials instead. The caller must be located in the same user
namespace hierarchy as the user namespace the overlayfs instance will
be mounted in. This provides a consistent and simple security model.
With this it is possible to e.g., mount an overlayfs instance where
the mounter must have CAP_SYS_ADMIN but the credentials used for
override_creds() have dropped CAP_SYS_ADMIN. It also allows the usage
of custom fs{g,u}id different from the callers and other tweaks"
* tag 'vfs-6.15-rc1.overlayfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
selftests/ovl: add third selftest for "override_creds"
selftests/ovl: add second selftest for "override_creds"
selftests/filesystems: add utils.{c,h}
selftests/ovl: add first selftest for "override_creds"
ovl: allow to specify override credentials
