Re: [PATCH] bug in setpgid()? process groups and thread groups

From: Alan Cox (alan@lxorguk.ukuu.org.uk)
Date: Sat Aug 02 2003 - 15:51:24 EST


On Sad, 2003-08-02 at 20:08, Roland McGrath wrote:
> The problem exists with uids/gids as well, in the sense that they are
> changed per-thread but POSIX semantics are that setuid et al affect the
> whole process (i.e. all threads in a thread group). I emphatically agree
> that this should be changed, and I hope we can get it done in 2.6.

There are two reasons the uid/gid stuff can't change.

#1 Lots of non posix afflicted intelligent programmers use the per
thread uid stuff in daemons. Its really really useful

#2 Linux fundamentally assumes your security credentials don't change
mid syscall except in the specific calls we intend to.

#2 is not sanely soluble for 2.6, and of questionable value anyway, #1
is a very good reason for making libc fix up this obscure posix
stupidity itself.

Lets face it how many posix pthreads app have -performance critical
setuid/getid calls ?

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