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1 | 28cc354f | Iustin Pop | Security in Ganeti |
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2 | 6884c0ca | Iustin Pop | ================== |
3 | 28cc354f | Iustin Pop | |
4 | 28cc354f | Iustin Pop | Ganeti was developed to run on internal, trusted systems. As such, the |
5 | 28cc354f | Iustin Pop | security model is all-or-nothing. |
6 | 28cc354f | Iustin Pop | |
7 | 28cc354f | Iustin Pop | All the Ganeti code runs as root, because all the operations that Ganeti |
8 | bd028152 | Iustin Pop | is doing require privileges: creating logical volumes, drbd devices, |
9 | 28cc354f | Iustin Pop | starting instances, etc. Running as root does not mean setuid, but that |
10 | 28cc354f | Iustin Pop | you need to be root to run the cluster commands. |
11 | 28cc354f | Iustin Pop | |
12 | 28cc354f | Iustin Pop | Host issues |
13 | 28cc354f | Iustin Pop | ----------- |
14 | 28cc354f | Iustin Pop | |
15 | 4fbe765c | Michael Hanselmann | For a host on which the Ganeti software has been installed, but not joined to a |
16 | 4fbe765c | Michael Hanselmann | cluster, there are no changes to the system. |
17 | 28cc354f | Iustin Pop | |
18 | 28cc354f | Iustin Pop | For a host that has been joined to the cluster, there are very important |
19 | 28cc354f | Iustin Pop | changes: |
20 | 6884c0ca | Iustin Pop | |
21 | 6884c0ca | Iustin Pop | - The host will have its SSH host key replaced with the one of the |
22 | 6884c0ca | Iustin Pop | cluster (which is the one the initial node had at the cluster |
23 | 6884c0ca | Iustin Pop | creation) |
24 | 6884c0ca | Iustin Pop | - A new public key will be added to root's authorized_keys file, |
25 | 6884c0ca | Iustin Pop | granting root access to all nodes of the cluster. The private part of |
26 | 6884c0ca | Iustin Pop | the key is also distributed to all nodes. Old files are renamed. |
27 | 6884c0ca | Iustin Pop | - Communication between nodes is encrypted using SSL/TLS. A common key |
28 | 6884c0ca | Iustin Pop | and certificate combo is shared between all nodes of the cluster. At |
29 | 6884c0ca | Iustin Pop | this time, no CA is used. |
30 | 6884c0ca | Iustin Pop | - The Ganeti node daemon will accept RPC requests from any host within |
31 | 6884c0ca | Iustin Pop | the cluster with the correct certificate, and the operations it will |
32 | 6884c0ca | Iustin Pop | do as a result of these requests are: |
33 | 6884c0ca | Iustin Pop | |
34 | 6884c0ca | Iustin Pop | - running commands under the /etc/ganeti/hooks directory |
35 | 6884c0ca | Iustin Pop | - creating DRBD disks between it and the IP it has been told |
36 | 6884c0ca | Iustin Pop | - overwrite a defined list of files on the host |
37 | 28cc354f | Iustin Pop | |
38 | 28cc354f | Iustin Pop | As you can see, as soon as a node is joined, it becomes equal to all |
39 | 28cc354f | Iustin Pop | other nodes in the cluster, and the security of the cluster is |
40 | 28cc354f | Iustin Pop | determined by the weakest node. |
41 | 28cc354f | Iustin Pop | |
42 | 4fbe765c | Michael Hanselmann | Note that only the SSH key will allow other machines to run random |
43 | 28cc354f | Iustin Pop | commands on this node; the RPC method will run only: |
44 | 6884c0ca | Iustin Pop | |
45 | 6884c0ca | Iustin Pop | - well defined commands to create, remove, activate logical volumes, |
46 | 6884c0ca | Iustin Pop | drbd devices, start/stop instances, etc; |
47 | 6884c0ca | Iustin Pop | - run SSH commands on other nodes in the cluster, again well-defined |
48 | 6884c0ca | Iustin Pop | - scripts under the /etc/ganeti/hooks directory |
49 | 28cc354f | Iustin Pop | |
50 | 28cc354f | Iustin Pop | It is therefore important to make sure that the contents of the |
51 | 28cc354f | Iustin Pop | /etc/ganeti/hooks directory is supervised and only trusted sources can |
52 | 28cc354f | Iustin Pop | populate it. |
53 | 28cc354f | Iustin Pop | |
54 | 28cc354f | Iustin Pop | Cluster issues |
55 | 28cc354f | Iustin Pop | -------------- |
56 | 28cc354f | Iustin Pop | |
57 | 28cc354f | Iustin Pop | As told above, there are multiple ways of communication between cluster |
58 | 28cc354f | Iustin Pop | nodes: |
59 | 6884c0ca | Iustin Pop | |
60 | 6884c0ca | Iustin Pop | - SSH-based, for high-volume traffic like image dumps or for low-level |
61 | 6884c0ca | Iustin Pop | command, e.g. restarting the Ganeti node daemon |
62 | 6884c0ca | Iustin Pop | - RPC communication between master and nodes |
63 | 6884c0ca | Iustin Pop | - DRBD real-time disk replication traffic |
64 | 28cc354f | Iustin Pop | |
65 | 4fbe765c | Michael Hanselmann | The SSH traffic is protected (after the initial login to a new node) by |
66 | 4fbe765c | Michael Hanselmann | the cluster-wide shared SSH key. |
67 | 28cc354f | Iustin Pop | |
68 | 4fbe765c | Michael Hanselmann | RPC communication between the master and nodes is protected using SSL/TLS |
69 | 6884c0ca | Iustin Pop | encryption. Both the client and the server must have the cluster-wide |
70 | 4fbe765c | Michael Hanselmann | shared SSL/TLS certificate and verify it when establishing the connection |
71 | 4fbe765c | Michael Hanselmann | by comparing fingerprints. We decided not to use a CA to simplify the |
72 | 4fbe765c | Michael Hanselmann | key handling. |
73 | 28cc354f | Iustin Pop | |
74 | 6884c0ca | Iustin Pop | The DRBD traffic is not protected by encryption, as DRBD does not |
75 | 6884c0ca | Iustin Pop | support this. It's therefore recommended to implement host-level |
76 | 888891c7 | Michael Hanselmann | firewalling or to use a separate range of IP addresses for the DRBD |
77 | 888891c7 | Michael Hanselmann | traffic (this is supported in Ganeti) which is not routed outside the |
78 | 6884c0ca | Iustin Pop | cluster. DRBD connections are protected from connecting due to bugs to |
79 | 6884c0ca | Iustin Pop | other machines, and from accepting connections from other machines, by |
80 | 6884c0ca | Iustin Pop | using a shared secret, exchanged via RPC requests from the master to the |
81 | 6884c0ca | Iustin Pop | nodes when configuring the device. |
82 | 6884c0ca | Iustin Pop | |
83 | 6884c0ca | Iustin Pop | Master daemon |
84 | 6884c0ca | Iustin Pop | ------------- |
85 | 6884c0ca | Iustin Pop | |
86 | 6884c0ca | Iustin Pop | The command-line tools to master daemon communication is done via an UNIX |
87 | 6884c0ca | Iustin Pop | socket, whose permissions are reset to ``0600`` after listening but before |
88 | 6884c0ca | Iustin Pop | serving requests. This permission-based protection is documented and works on |
89 | 6884c0ca | Iustin Pop | Linux, but is not-portable; however, Ganeti doesn't work on non-Linux system at |
90 | 6884c0ca | Iustin Pop | the moment. |
91 | 4fbe765c | Michael Hanselmann | |
92 | 4fbe765c | Michael Hanselmann | Remote API |
93 | 4fbe765c | Michael Hanselmann | ---------- |
94 | 4fbe765c | Michael Hanselmann | |
95 | 4fbe765c | Michael Hanselmann | Starting with Ganeti 2.0, Remote API traffic is encrypted using SSL/TLS by |
96 | 4fbe765c | Michael Hanselmann | default. It supports Basic authentication as per RFC2617. |
97 | 4fbe765c | Michael Hanselmann | |
98 | 4fbe765c | Michael Hanselmann | Paths for certificate, private key and CA files required for SSL/TLS will |
99 | 4fbe765c | Michael Hanselmann | be set at source configure time. Symlinks or command line parameters may |
100 | 4fbe765c | Michael Hanselmann | be used to use different files. |