X-Git-Url: https://git.ralfj.de/schsh.git/blobdiff_plain/3ea74a5b2af056f364aaa411c76e879aec397439..f904a13d8172b27f6a1ceeb78673d3261c3783f1:/README.rst diff --git a/README.rst b/README.rst deleted file mode 100644 index d7f108b..0000000 --- a/README.rst +++ /dev/null @@ -1,101 +0,0 @@ -schsh: Restricted file access via SSH -===================================== - -Introduction ------------- - -Welcome to schsh_, a schroot-based shell. - -Its purpose is simple: I want to provide users with scp, sftp and rsync access -to my server, such that they can only operate in a certain subdirectory. -There are plenty of solutions for this problem out there, and all have one -drawback in common: -You need to manually set up a bunch of chroots, and copy the files needed for -scp, sftp and rsync into them. - -I didn't like that, so here is my alternative solution: Use schroot for the -chroots. This gets OpenSSH out of the loop when it comes to chroots, instead -the relevant users get a special shell (schsh, the schroot shell). That shell -essentially calls schroot and runs the desired command inside the chroot. It -also provides some very basic command restriction (so that you can allow scp, -sftp and rsync and nothing else). - -Unfortunately, this still needs a (s)chroot to be set up for each user, but at -least no files have to be copied: Instead, schroot is configured to bind-mount -the relevant system folders into the user-chroot. Hence no files are -duplicated, and system updates to the relevant tools are applied inside the -chroots automatically. For additional hardening, these bind-mounts are -configured to be read-only and no-setuid, while the only user-writeable folder -is no-exec. - -.. _schsh: https://www.ralfj.de/projects/schsh - -Setup ------ - -Before you start, make sure you have the dependencies installed: -schsh needs `Python 3`_ (I tested it with version 3.2) and -schroot_ (version 1.6 or newer). - -Installation is simple: Just run ``make install``. That will copy some files -to ``/usr/local/bin``, and some configuration to ``/etc/schroot/``. -Before you create any users, make sure the directory ``/var/lib/schsh`` and a -group called ``schsh`` exist. - -You should also set up SSH to disallow port forwarding for users controlled by -schsh. See ``sshd_config`` in the source folder for an appropriate snippet -of OpenSSH configuration. - -Before you can set up schsh for a user, you need to create it first:: - - adduser sandboxed --disabled-password - -Any existing user can be "sandboxed" by running:: - - makeschsh sandboxed - -This does the following: - -* Change the user's shell to ``/usr/local/bin/schsh`` -* Create a chroot base in ``/var/lib/schsh/sandboxed`` with some empty - subfolders as well as ``/etc/passwd`` and ``/etc/group`` containing - only root, this user and the ``schsh`` group -* Add the user to the ``schsh`` group -* Set up a schroot called ``schsh-sandboxed`` for the given folder, and an - fstab file in ``/etc/schroot/schsh`` used by this schroot - -Now if the user logs in via SSH, ``/usr/local/bin/schsh`` will be executed, -and it will lock the user into the schroot ``schsh-sandboxed``. It will -only see some system folders and a folder called ``/data`` mapped to -``/home/sandboxed/data``. If you want to give the user access to more -folders, or another folder, simply edit ``/etc/schroot/schsh/sandboxed.fstab``. -The only part of schsh writing any files is ``makeschsh``, so you can change -the users' schroot configurations at your will. - -.. _Python 3: http://www.python.org -.. _schroot: https://wiki.debian.org/Schroot - -Configuration -------------- - -There is not much to configure at the moment. However, there are some -global variables at the top of both ``schsh`` and ``makeschsh`` to -change the base paths, and to tell which commands are allowed. - -Source, License ---------------- - -You can find the sources in the `git repository`_ and `on GitHub`_. They are -provided under the GPLv3_. In addition, all files except for ``schsh-rrsync`` -are provided under the GPLv2_ or (at your option) any later version of the GPL. - -.. _git repository: http://www.ralfj.de/git/schsh.git -.. _on GitHub: https://github.com/RalfJung/schsh -.. _GPLv2: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html -.. _GPLv3: https://www.gnu.org/licenses/gpl.html - -Contact -------- - -If you found a bug, or want to leave a comment, please -`send me a mail `_.