All you need do

All you need to do is ask. Your version could work but it’s old, odd, akward, formal.

No All you need *to* do is ask

This is still standard but somewhat formal and antiquated sounding in 2024. Until about 60 years ago the bare infinitive and the complete infinitive forms were about equally common in this context, but since then the complete infinitive has come to predominate.

It is possible because *need* is a semi-model verb and need not use *to* when it functions as an auxiliary verb. Nevertheless, many people would perceive it as an error.

"All you need do" sounds like it should only be said with a mid-Atlantic accent.