• Mike Hibler's avatar
    Support for per-experiment root keypairs (Round 1). See issue #302. · c6150425
    Mike Hibler authored
    Provide automated setup of an ssh keypair enabling root to login without
    a password between nodes. The biggest challenge here is to get the private
    key onto nodes in such a way that a non-root user on those nodes cannot
    obtain it. Otherwise that user would be able to ssh as root to any node.
    This precludes simple distribution of the private key using tmcd/tmcc as
    any user can do a tmcc (tmcd authentication is based on the node, not the
    This version does a post-imaging "push" of the private key from boss using
    ssh. The key is pushed from tbswap after nodes are imaged but before the
    event system, and thus any user startup scripts, are started. We actually
    use "pssh" (really "pscp") to scale a bit better, so YOU MUST HAVE THE
    PSSH PACKAGE INSTALLED. So be sure to do a:
        pkg install -r Emulab pssh
    on your boss node. See the new utils/pushrootkeys.in script for more.
    The public key is distributed via the "tmcc localization" command which
    was already designed to handle adding multiple public keys to root's
    authorized_keys file on a node.
    This approach should be backward compatible with old images. I BUMPED THE
    VERSION NUMBER OF TMCD so that newer clients can also get back (via
    rc.localize) a list of keys and the names of the files they should be stashed
    in. This is used to allow us to pass along the SSL and SSH versions of the
    public key so that they can be placed in /root/.ssl/<node>.pub and
    /root/.ssh/id_rsa.pub respectively. Note that this step is not necessary for
    inter-node ssh to work.
    Also passed along is an indication of whether the returned key is encrypted.
    This might be used in Round 2 if we securely implant a shared secret on every
    node at imaging time and then use that to encrypt the ssh private key such
    that we can return it via rc.localize. But the client side script currently
    does not implement any decryption, so the client side would need to be changed
    again in this future.
    The per experiment root keypair mechanism has been exposed to the user via
    old school NS experiments right now by adding a node "rootkey" method. To
    export the private key to "nodeA" and the public key to "nodeB" do:
        $nodeA rootkey private 1
        $nodeB rootkey public 1
    This enables an asymmetric relationship such that "nodeA" can ssh into
    "nodeB" as root but not vice-versa. For a symmetric relationship you would do:
        $nodeA rootkey private 1
        $nodeB rootkey private 1
        $nodeA rootkey public 1
        $nodeB rootkey public 1
    These user specifications will be overridden by hardwired Emulab restrictions.
    The current restrictions are that we do *not* distribute a root pubkey to
    tainted nodes (as it opens a path to root on a node where no one should be
    root) or any keys to firewall nodes, virtnode hosts, delay nodes, subbosses,
    storagehosts, etc. which are not really part of the user topology.
    For more on how we got here and what might happen in Round 2, see: