I would say that we use 'can' and 'can't' more about ability than about permission.
"David Luiz cannot defend for toffee," does not mean that he is not allowed to defend for or by some sweets. It means he is useless at defending. (The phrase 'cannot do [something} for toffee means that somebody absolutely cannot do something.'
If you are confused about the dual usage, then my best suggestion would be to stick to 'can,' when you are talking about ability and to use the verb "to allow," when you are talking about permission.
"David Luiz cannot defend well."
"The goalkeeper is not allowed to use his hands outside of the penalty area."