> Currently, Grsecurity is a commercial product and is distributed only to paying customers. My understanding from several reliable sources is that customers are verbally or otherwise warned that if they redistribute the Grsecurity patch, as would be their right under the GPL, that they will be assessed a penalty: they will no longer be allowed to be customers, and will not be granted access to any further versions of Grsecurity. GPL version 2 section 6 explicitly prohibits the addition of terms such as this redistribution prohibition.
This is a fundamental misunderstanding of the GPL. The GPL merely requires corresponding source to be made available alongside binaries, so if you get a binary from someone you have a right to the corresponding source from that person. It does not require anyone to offer you a binary; it merely says if they did, you can get the corresponding source.
GRSecurity has no obligation to provide you a binary, they can decline to offer you one because you have a silly walk or a 13-character username or you exercised your rights under the GPL. The GPL does not entitle you to product updates or to continue to be a customer of someone who doesn't want you as a customer, it merely entitles you to corresponding source for binaries.
Some would say GRSecurity's practice violates the spirit of the GPL, but the GPL is not a spiritual entity, it's a legal document, and if you want a legal document that produces a different outcome you can write one up.
Also, you should read the fine print from any other Linux vendor – RHEL, Oracle, etc. You don't have to go on "my understanding from several reliable sources", the documents actually state they'll terminate you as a customer if you redistribute their stuff.