authunix_create_default: tooo many

[Carl Smith]

> From: steve at polyslo.CalPoly.EDU (Steve DeJarnett)
> Subject: Re: authunix_create_default: tooo many
> 
> 	This is a "problem" with NFS (actually, I think the problem is 
> actually due to a limitation in a table size in the RPC stuff somewhere, but
> I'm not positive).  Basically, there's a table that holds a list of all of
> the groups you belong to.  Some far-sighted individual at Sun (I suspect) 
> decided long ago that no one in their right minds would be in more than 8
> groups, so they set the maximum number of groups to 8 (I suspect that there's
> an array lurking in the code that is predefined to have only 8 entries).  
> What appears to be happening is that your account 'root' (or some other uid-0
> account you're trying to do this from) belongs to more than 8 groups, and 
> when trying to do NFS-related work, it dies because of an RPC error due to 
> the fact that you belong to > 8 groups.
> 
> 	I'm told that more recent versions of NFS/RPC have this limitation
> removed from them, but I don't know this for certain, as I only belong to 7
> groups on our Suns :-).
> 
> 	Hope that helps some (I also hope I didn't make any major screwups in
> the description).

	Esentially correct.  Early versions of the RPC authentication code
believed in a maximum of 8 groups (by the way, this number for the maximum
number of groups to which a user may belong came from 4.2BSD, not Sun).
The RPC protocol itself specifies a maximum of 10 groups in AUTH_UNIX-style
authentication.  Through the incredible naivete of some people at Sun who
should have known better, this number was changed to 16 in SunOS 4.x and
NFSSRC 4.0.  You are seeing the more benign of those affects.  Other programs
(those less inclined to do range checking than the kernel) may dump core when
confonted with more than 8 groups.  To ensure interoperability among the myriad
NFS implementation in the world today, use the most restrictive assumption
(i.e., no more than 8 groups).  We will fix this when the RPC protocol itself
is revved.

			Carl