Commit 6884c0ca authored by Iustin Pop's avatar Iustin Pop
Browse files

Updates to the security document

This patch changes formatting and the DRBD shared secret details, and
adds master daemon socket details to the security doc.

Reviewed-by: imsnah
parent 73100cf5
Security in Ganeti
~~~~~~~~~~~~~~~~~~
==================
Ganeti was developed to run on internal, trusted systems. As such, the
security model is all-or-nothing.
......@@ -17,21 +17,23 @@ cluster, there are no changes to the system.
For a host that has been joined to the cluster, there are very important
changes:
- The host will have its SSH host key replaced with the one of the
cluster (which is the one the initial node had at the cluster
creation)
- A new public key will be added to root's authorized_keys file, granting
root access to all nodes of the cluster. The private part of the key
is also distributed to all nodes. Old files are renamed.
- Communication between nodes is encrypted using SSL/TLS. A common
key and certificate combo is shared between all nodes of the cluster.
At this time, no CA is used.
- The Ganeti node daemon will accept RPC requests from any host within the
cluster with the correct certificate, and the operations it will do as a
result of these requests are:
- running commands under the /etc/ganeti/hooks directory
- creating DRBD disks between it and the IP it has been told
- overwrite a defined list of files on the host
- The host will have its SSH host key replaced with the one of the
cluster (which is the one the initial node had at the cluster
creation)
- A new public key will be added to root's authorized_keys file,
granting root access to all nodes of the cluster. The private part of
the key is also distributed to all nodes. Old files are renamed.
- Communication between nodes is encrypted using SSL/TLS. A common key
and certificate combo is shared between all nodes of the cluster. At
this time, no CA is used.
- The Ganeti node daemon will accept RPC requests from any host within
the cluster with the correct certificate, and the operations it will
do as a result of these requests are:
- running commands under the /etc/ganeti/hooks directory
- creating DRBD disks between it and the IP it has been told
- overwrite a defined list of files on the host
As you can see, as soon as a node is joined, it becomes equal to all
other nodes in the cluster, and the security of the cluster is
......@@ -39,10 +41,11 @@ determined by the weakest node.
Note that only the SSH key will allow other machines to run random
commands on this node; the RPC method will run only:
- well defined commands to create, remove, activate logical volumes,
drbd devices, start/stop instances, etc;
- run SSH commands on other nodes in the cluster, again well-defined
- scripts under the /etc/ganeti/hooks directory
- well defined commands to create, remove, activate logical volumes,
drbd devices, start/stop instances, etc;
- run SSH commands on other nodes in the cluster, again well-defined
- scripts under the /etc/ganeti/hooks directory
It is therefore important to make sure that the contents of the
/etc/ganeti/hooks directory is supervised and only trusted sources can
......@@ -53,27 +56,38 @@ Cluster issues
As told above, there are multiple ways of communication between cluster
nodes:
- SSH-based, for high-volume traffic like image dumps or for low-level
command, e.g. restarting the Ganeti node daemon
- RPC communication between master and nodes
- DRBD real-time disk replication traffic
- SSH-based, for high-volume traffic like image dumps or for low-level
command, e.g. restarting the Ganeti node daemon
- RPC communication between master and nodes
- DRBD real-time disk replication traffic
The SSH traffic is protected (after the initial login to a new node) by
the cluster-wide shared SSH key.
RPC communication between the master and nodes is protected using SSL/TLS
encryption. Both the client and the server must have the cluster-widely
encryption. Both the client and the server must have the cluster-wide
shared SSL/TLS certificate and verify it when establishing the connection
by comparing fingerprints. We decided not to use a CA to simplify the
key handling.
The DRBD traffic is not protected by encryption. DRBD does not support
traffic encryption. It's therefore recommended to implement host-level
The DRBD traffic is not protected by encryption, as DRBD does not
support this. It's therefore recommended to implement host-level
firewalling or to use a separate range of IP addresses for the DRBD
traffic (this is supported in Ganeti) which is not routed outside the
cluster. DRBD connections are protected from connecting to random other
machines by using a shared secret exchanged via RPC requests when
starting the device.
cluster. DRBD connections are protected from connecting due to bugs to
other machines, and from accepting connections from other machines, by
using a shared secret, exchanged via RPC requests from the master to the
nodes when configuring the device.
Master daemon
-------------
The command-line tools to master daemon communication is done via an UNIX
socket, whose permissions are reset to ``0600`` after listening but before
serving requests. This permission-based protection is documented and works on
Linux, but is not-portable; however, Ganeti doesn't work on non-Linux system at
the moment.
Remote API
----------
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment