Security issue with SSL termination. Recommend SSL termination proxy or allow changing uid/gui of process.

[dol]

websockify has IMHO a security flaw when it come to the use of SSL.

On any systems, it's recommended, to restrict the access to the SSL key and certificate. On Debian systems, all the keys and certs under /etc/ssl/private/ are only readable by the root user. First solution: websockify has to be started as root user to be able to read the certificate information under /etc/ssl/private/. If websockify has a vulnerability (yet or in the future, hope not), it might be possible to gain root access. The second solution is to create a specific user for the websockify service, similar to the 'www-data' user for Apache. In this case, the websockify user must be able to read the certificate on startup. This can only be achieved by granting 'world' access to the certificate under /etc/ssl/private/. This might break other applications using the same certificate and performing a check if the certificate permissions are correct. Some application don't even startup if the permission are incorrect.

The only solution to this problem is using a SSL termination proxy in front of websockify. 1.) Start websockify under a specific websockify system user listen to localhost:<websockifyPort> without SSL support -> sudo -u websockify /opt/local/websockify localhost:<websockifyPort> 2.) Use a SSL termination proxy like stunnel and setup the port binding setting like accept=<publicPort>, connect=localhost:<websockifyPort>

stunnel is one of the only SSL termination proxy that are capable dealing with websocket upgrades. NGINX has recently added websocket support.

An other possible solution is, to start the server as root, read the certificate in memory and change the uid/gid of the process. supervisord is doing this here. This can also be added to websockify here with a newly introduced parameter --user/--group.

[kanaka]

Yeah, that's a good point. Unfortunately, the ssl implementation in python takes file paths and not string data, so getting the cert data securely from one side of the setuid/fork to the other side will be non-trivial.

I won't have time to do this any time soon, but I'm certainly willing to take a well written/tested patch.

[dol]

Valid point.

Note for the future: According to this issue/patch this can be achieved in Python 3.2 with the use of SSL Contexts. For older Python versions, the use of pyOpenSSL might be a solution. pyOpenSSL is shipped as a package in most of the Linux distros.

[kanaka]

@Dol that's a good reference.

Does pyOpenSSL have a routine to wrap an existing non-SSL socket like the standard ssl module?

[dol]

According to this example and the documentation of Connection class it's possible. Guess this is what you where looking for. The 'Roundup Issue Tracker' project has a pyOpenSSL Server implementation with a privilege change of the uid/gid.

[markmont]

Here is a different approach, which uses a setuid wrapper program. I threw this together quickly, but if there is interest I could clean it up and implement it properly: https://bitbucket.org/umlsait/umich-python-websockify