From: Guillaume Marcais <guslist@...>
Date: 2004-05-20T03:41:26+09:00
Subject: Re: RCR: UNIX credentials

So, should we implement a UNIXSocket#getpeerid method, using getpeerid()
or SO_PEERCRED, depending on what's available? The way of doing things
with getpeerid seems more natural than SCM_CREDS. 

I'll resumit an RCR.

Guillaume.

On Wed, 2004-05-19 at 10:16, Tanaka Akira wrote:
> In article <1084926982.2388.130.camel@comp>,
>   Guillaume Marcais <guslist@free.fr> writes:
> 
> > The Linux system provide a mechanism to send UNIX credentials as
> > ancilary data (the same way as you can pass file descriptors,
> > implemented in Ruby as send_io). Other UNIX implementation I believe
> > offer similar mechanism.
> 
> I surveyed the feature sometime ago.
> Unfortunately it is not so portable.
> 
> 1. SCM_CREDS and getpeerid.
> 
>   There are 2 kind of interfaces.
>   SCM_CREDS: a client must send a credential explicitly.
>   getpeerid: a client doesn't need to send a credential.
> 
> 2. getpeerid
> 
>   As far as I know, following system has getpeerid or similar.
> 
>   FreeBSD 4.6 (LOCAL_PEERCRED, http://www.freebsd.org/cgi/cvsweb.cgi/src/lib/libc/gen/getpeereid.3)
>   OpenBSD 3.0 (http://www.openbsd.org/cgi-bin/man.cgi?query=getpeereid&sektion=2)
>   Linux (socket(7): getsockopt SO_PEERCRED)
>   MacOS X (http://www.hmug.org/man/3/getpeereid.html)
> 
>   DJB recommends getpeerid.
>   http://cr.yp.to/docs/secureipc.html
> 
> 2. SCM_CREDS
> 
>   As far as I know, following system has SCM_CREDS or similar.
>   However, credential information varies on each system.
> 
>   FreeBSD 3.0 (recvmsg(2): SCM_CREDS: pid, uid, euid, gid, supp groups)
>   NetBSD 1.4.0 (unix(4): LOCAL_CREDS, SCM_CREDS: uid, euid, gid, egid, supp groups: http://www.netbsd.org/Changes/changes-1.4.html)
>   OpenBSD 2.5 (SCM_CREDS: uid, euid, gid, egid, supp groups)
>   Linux (unix(7): SCM_CREDENTIALS: pid, uid, gid)
> 
> 3. send_io/recv_io may be usable for authentication.
> 
>   See: Secure UNIX Programming FAQ
>   4.4) How do I authenticate a non-parent process?
>   http://www.whitefang.com/sup/secure-faq.html
> -- 
> Tanaka Akira
>