Using thread-specific credentials on Linux in Samba with glibc.

[Jeremy Allison]

On Mon, Jul 02, 2012 at 03:10:53PM -0700, Roland McGrath wrote:
> > Just to make things extremely clear, what we're hoping for is
> > an acknowlegement from the glibc maintainers that using syscall()
> > in this way to get per-process thread credentials on Linux
> > platforms is allowed by glibc, in that if it gets accidently
> > broken in future by glibc changes (as can happen with any
> > software of course :-) then it would be considered a bug.
> 
> The context remains utterly muddy and we are not going to read a giant
> thread to tease out what you are asking.  Show us an example of a use of
> the syscall function that you are seeking a clarification on the validity of.

Sure, no problem. I want to be able to use this function:

----------------------------------------------------------
int samba_setresuid(uid_t ruid, uid_t euid, uid_t suid)
{
        return syscall(SYS_setresuid, ruid, euid, suid);
}
----------------------------------------------------------

to continue to set a credential on the current Linux thread
(which it currently does), not the whole POSIX process,
and for glibc to allow such use in the future.

Jeremy.