There were a lot of Germans who were in the dark about specific atrocities. But atrocities in general were well known. German soldiers weren't sent to the Eastern front to "defend the Fatherland", they were sent with signs everywhere that said they were off to "Thrash the Jews".
And with such a high number of attrocities committed by infantry soldiers, there is NO WAY that didn't filter back to the general populous. Again, not specifics, but incidents and generalities. The German people knew their soldiers were A-fighting a war of aggression, and B- up to no good. Yet tens of thousands went out to see their soldiers off, often times carrying anti Semitic signs themselves.
With such hatred being widespread, you'd have to be pretty ignorant to not know there were atrocities being committed. Let's face it, war brings out the worst in people. Sometimes it brings out the best. Sometimes it will be the worst and best in the same minute But bringing out the best is not nearly as common as bringing out the worst. And if there is widespread hatred in the air, what do you think is going to happen?
Example going on right now. Would you consider the supporters of ISIS in Iraq right now to be completely innocent? Nazi's were political rather than religious, but their beliefs were bordering on the religious, and their demands on a person's alignment and loyalty were as strong or stronger. ISIS supporters are the support system for the terrorists, just like the citizenry were the support system for the Nazi's.
Also consider there were a number of atrocities committed in Germany by both German government personnel, or committed by civilians while officials stood by and watched. Nearly a decade of persecution and stripping of rights, property, and dignity of Jews. So when they went off to war with banners proclaiming they were going to "thrash the jews", you'd have to have some serious denial issues to think it's not going to get out of hand. If the German people were in rehab, they'd be called "Enablers". While I believe there were some who were innocent, as a nation I consider them guilty at all levels.
As for the "Final Solution" I don't think many in the general population knew. I think people in the towns with the the death camps had to highly suspect, and probably did't want to know. Trains coming in with people, no trains going out, yet the worker population stays a general constant...simple math. But honestly I think they were just in denial; which is a bit understandable. That is something hard to wrap your head around.