[PATCH] Linux: Implement per-thread user and group IDs

[Florian Weimer]

* Florian Weimer:

> This functionality is needed by many file servers, including Samba and
> nfs-ganesha.
>
> The patch context depends on the earlier patch for per-thread file
> system attributes:
>
>   <https://sourceware.org/ml/libc-alpha/2018-11/msg00866.html>
>
> (Although there is no functional dependency.)
>
> The abilist diffs are not included in this patch because maintaining
> them causes too much churn.
>
> Thanks,
> Florian
>
> -----
> This commit adds the functions pthread_attr_setperthreadids_np and
> pthread_attr_getperthreadids_np.  Threads created with the new flag
> will be exempted from the setxid broadcast.  setuid and related
> functions will only update the credentials for the current thread.
>
> Multi-threaded file servers typically need this functionality and
> call the system calls directly to implement this.
>
> 2018-12-12  Florian Weimer  <fweimer@redhat.com>
>
> 	* sysdeps/nptl/pthread.h (pthread_attr_setperthreadids_np)
> 	(pthread_attr_getperthreadids_np): Declare.
> 	* nptl/Makefile (routines): Add pthread_attr_setperthreadids_np,
> 	pthread_attr_getperthreadids_np.
> 	* nptl/Versions (GLIBC_2.29): Export

Ping?

Original patch: <https://sourceware.org/ml/libc-alpha/2018-12/msg00461.html>

Do we want this at all?  If yes, I will rebase the patch to current
master and resubmit.

Thanks,
Florian