[Nut-upsuser] SSL only working in DEBUG mode

Emilien Kia kiae.dev at gmail.com
Wed Mar 25 17:47:58 UTC 2015

2015-03-21 17:06 GMT+01:00 Melkor Lord <melkor.lord at gmail.com>:

> On Fri, Mar 20, 2015 at 4:40 PM, Emilien Kia <kiae.dev at gmail.com> wrote:
> Some precisions:
>> we are not alone, some projects had similar problem:
>> http://bugs.bitlbee.org/bitlbee/ticket/785
>> And the problem is really coming from NSS initialization. Discussion
>> about the issue here :
>> http://osdir.com/ml/mozilla.crypto/2002-08/msg00016.html
> Wow! Congratulations on finding the source of the problem, I bet this
> wasn't easy!

You have done the hardest job. Once you isolate the problem occurs only
when running as a deamon and not in debug mode, searching for a problem is
Moreover we have done so many tests on this feature that it is really
surprising we didn't detect this problem before.
But when we look more precisely at DVT linked by Charles, we can see we did
test only in direct mode, not in deamonized mode.

> I'm glad to see that NUT isn't faulty :-)
>> There is a workaround to use NSS with fork but it is more setting a flag
>> to share some resources (primarily sockets) but must (re)initialize NSS
>> library on all children.
>> AFAIK why we initialize NSS library before becoming user and forking is
>> to be able to access and read certificates and keys which is readable only
>> by root and should not be readable in userland. This behavior is this
>> because it was the behavior used when using OpenSSL. Modifying this
>> behavior implies to modify key/certificate storage and acces right policy.
> Well, NUT uses a dedicated unpriviledged user to run ("nut" in my case) so
> why not initialize the SSL stuff after forking?
> Before forking, just check that the SSL cert/key files belong to the same
> user as the user which started "upsd" and throw an error message to the
> logs if it's not the case to warn the user. Then it's your decision whether
> to "disable SSL usage" and continue or refuse "upsd" execution if
> conditions are not met.
I will look to do something like that.

> If it's convenient, make this part NSS dependent with the usual #ifdef
> spaghetti :-) to avoid influence on the OpenSSL code.

What I will do is to move ssl initializing after usering and forking, than
add key file right checking where ssl was initialized before (before
As keys should be owned by nut user, this would not be a problem.
And moving this code, independently of SSL implementation (OpenSSL or NSS)
should work. And will not add more code implementation dependent.

Charles, Arnaud ? Ok with that ?


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