Re: [RFC] connectat()/bindat() or an alternative design

[Cong Wang <cwang@multikernel.io>]

Hi John,

On Mon, May 18, 2026 at 03:09:43PM -0400, John Ericson wrote:
> Hello, I am interested in seeing something like the BSD's connectat/bindat in
> Linux.
> 
> The deficiencies with traditional `bind`/`connect` for unix sockets are
> well-known. The advantages of openat2 over openat over open are also well-known, so I
> won't waste anyone's time restating either.
> 
> https://lore.kernel.org/netdev/4FCF171B.8000207@parallels.com/
> https://lore.kernel.org/all/CAEnbY+co6YLXANfeMnfBOBs8Ba_Sbdqz0Ahm8RzAhRF7MrxL4Q@mail.gmail.com/
> 
> Here are two previous times this was raised, unfortunately with no replies.
> Hoping this third time is the charm!
> 
> To hopefully give the discussion a bit more concreteness, I have taken a stab at
> two refactors (with an LLM, full disclosure) to get a sense of what the
> approaches look like. (To be clear, these are not patches I am trying to
> formally submit, these are just sketches to guide the conversation. I haven't
> built or tested them, just read them.)
> 

Thanks for bringing this up.

I have no doubt connectat()/bindat() helps closing TOCTOU for Unix
sockets. However, it would be nicer to describe your use case here,
especially what the problems are without it. This would help more to
jusify your proposal here than just getting aligned with openat() or
BSD.

Hope this helps.

Regards,
Cong