genode/repos/os/src/server/lx_fs

This directory contains an Genode file-system service to Linux host fs
wrapper.

Configuration
~~~~~~~~~~~~~

Access to the file system can be tailored for each session depending on the
session's label. By default, no permissions are granted to any session.
To selectively permit access to (a part of) the file system, at least one
policy must be defined.

The following configuration illustates the way of how to express policy.

! <config>
!   <!-- constrain sessions according to their labels -->
!   <policy label="noux -> root" root="/" />
!   <policy label="noux -> home" root="/home/user" writeable="yes" />
!   <policy label="noux -> tmp"  root="/tmp"       writeable="yes" />
! </config>

Session-specific access-control policy is expressed via one or more '<policy>'
nodes. At session-creation time, each policy node is matched against the label
of the new session. If the label of a policy node matches, the defined policy
is applied. If multiple policies match, the one with the longest 'label'
attribute (the most specific one) is selected.

A policy node may contain the following attributes. The mandatory 'root'
attribute defines the viewport of the session onto the file system. The
optional 'writeable' attribute grants the permission to modify the file system.


Example
~~~~~~~

To illustrate the use of lx_fs, refer to the 'base-linux/run/lx_fs.run'
script.


Notes
~~~~~

If the Linux file system experiences changes from other processes
'inotify' may help to keep the servers cache up-to-date. This is not
implemented yet.