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Re: Socket activation for GitWeb FastCGI with systemd?





03.04.2018, 23:04, "Jacob Keller" <jacob.keller@xxxxxxxxx>:
> On Tue, Apr 3, 2018 at 11:53 AM, Alex Ivanov <gnidorah@xxxxx> wrote:
>>  Hi.
>>  I want to use systemd as fastcgi spawner for gitweb + nginx.
>>  The traffic is low and number of users is limited + traversal bots. For that reason I've decided to use following mimimal services
>>
>>  gitweb.socket
>>  [Unit]
>>  Description=GitWeb Socket
>>
>>  [Socket]
>>  ListenStream=/run/gitweb.sock
>>  Accept=false
>>
>>  [Install]
>>  WantedBy=sockets.target
>>
>>  gitweb.service
>>  [Unit]
>>  Description=GitWeb Service
>>
>>  [Service]
>>  Type=simple
>>  ExecStart=/path/to/gitweb.cgi --fcgi
>>  StandardInput=socket
>>
>>  However this scheme is not resistant to simple DDOS.
>>  E.g. traversal bots often kill the service by opening non existing path (e.g http://host/?p=repo;a=blob;f=nonexisting/path;hb=HEAD showing in browser 404 - Cannot find file) many times consecutively, which leads to
>>  Apr 03 21:32:10 host systemd[1]: gitweb.service: Start request repeated too quickly.
>>  Apr 03 21:32:10 host systemd[1]: gitweb.service: Failed with result 'start-limit-hit'.
>>  Apr 03 21:32:10 host systemd[1]: Failed to start GitWeb service.
>>  and 502 Bad Gateway in browser. I believe the reason is that gitweb.service dies on failure and if it happens too often, systemd declines to restart the service due to start limit hit.
>>  So my question is how to correct systemd services for GitWeb to be resistant to such issue? I prefer to use single process to process all clients.
>>  Thanks.
>
> This sounds like a systemd specific question that might get a better
> answer from the systemd mailing list.

Thanks I will try that too.

>
> That being said, I believe if in this case gitweb is dying due to the
> path not existing? You might be able to configure systemd to
> understand that the particular exit code for when the path doesn't
> exist is a "valid" exit, and not a failure case..

I will try to do that, but I'm afraid that there may be other ways to remotely abuse the service.

>
> I'm not entirely understanding your goal.. you want each request to
> launch the gitweb process, and when it's done you want it to exit? But
> if there are multiple connections at once you want it to stay alive
> until it services them all? I think the best answer is configure
> systemd to understand that the exit code for when the path is invalid
> will be counted as a success.

I want a single process for all connections too keep RAM usage at minimal. I also though it fits my case since number of users is low.

>
> Thanks,
> Jake