x/sys/unix: want more platform support for UNIX domain socket peer credentials

[gdamore]

What version of Go are you using (go version)?

$ go version
PS C:\Users\garre> go version
go version go1.14.4 windows/amd64

(Although I use many different versions of Go on illumos, Linux, darwin, etc.)

Does this issue reproduce with the latest release?

Yes.

What operating system and processor architecture are you using (go env)?

go env Output

$ go env

Feature request

As this is a feature request, I'm not including typical bug report details.

What I'd like is a way for us to obtain peer credentials more broadly. I am most interested in illumos/solaris (which uses getpeerucred() in libc, but I see this being useful for Darwin, FreeBSD, and possibly others.

With Linux we can do GetsockoptUcred with SO_PEERCRED. Which is great. I would like to have a similar way to do this for other platforms (platform specific probably) without having to resort to cgo if possible.

[ianlancetaylor]

What are the mechanisms available on other systems?

[gdamore]

So Solaris and illumos have getpeerucred. I believe BSD systems have SO_LOCAL and LOCAL_PEERCRED and LOCAL_PEERPID. There is also a version of SO_PEERCRED that uses sockpeercred instead of ucred.

This is a mess of non portable APIs. But it would be nice if I could access this tags and not have to resort to cgo.

[gopherbot]

Change https://golang.org/cl/294989 mentions this issue: unix: add Xucred, GetsockoptXucred on freebsd

[tklauser]

FWIW, https://golang.org/cl/292330 added this for Darwin already, courtesy of @bradfitz . I'm about to send CLs adding support on the BSDs and possibly Illumos/Solaris as well.

Once these landed in x/sys/unix, I hope we can add support for these additional platforms to inet.af/peercred as well which provides a portable API for peer credentials.

[MagicalTux]

This was initially requested in #1101, however that issue was hijacked to instead cover sending over credentials and file descriptors, and it deemed resolved in 2017.

This would be really nice to have a cross platform API for this.

[gopherbot]

Change https://go.dev/cl/669835 mentions this issue: unix: add PID to Xucred on FreeBSD