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SubjectRe: [PATCH] ifdef struct task_struct::security
On Mon, 6 Aug 2007 15:31:12 -0500 "Serge E. Hallyn" <serge@hallyn.com> wrote:

> Quoting Alexey Dobriyan (adobriyan@gmail.com):
> > For those who don't care about CONFIG_SECURITY.
>
> I'm quite sure we started that way, but the ifdefs were considered
> too much of an eyesore.

argh, y'all stop top-posting at me.

> If this is now acceptable, then the same thing might be considered
> for inode->i_security, kern_ipc_perm.security, etc. Getting rid of
> just the task->security seems overly half-hearted.
>
> -serge
>
> > Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
> > ---
> >
> > include/linux/sched.h | 3 ++-
> > kernel/fork.c | 2 ++
> > 2 files changed, 4 insertions(+), 1 deletion(-)
> >
> > --- a/include/linux/sched.h
> > +++ b/include/linux/sched.h
> > @@ -1086,8 +1086,9 @@ struct task_struct {
> > int (*notifier)(void *priv);
> > void *notifier_data;
> > sigset_t *notifier_mask;
> > -
> > +#ifdef CONFIG_SECURITY
> > void *security;
> > +#endif
> > struct audit_context *audit_context;
> > seccomp_t seccomp;
> >
> > --- a/kernel/fork.c
> > +++ b/kernel/fork.c
> > @@ -1066,7 +1066,9 @@ static struct task_struct *copy_process(unsigned long clone_flags,
> > do_posix_clock_monotonic_gettime(&p->start_time);
> > p->real_start_time = p->start_time;
> > monotonic_to_bootbased(&p->real_start_time);
> > +#ifdef CONFIG_SECURITY
> > p->security = NULL;
> > +#endif
> > p->io_context = NULL;
> > p->io_wait = NULL;
> > p->audit_context = NULL;
> >

I think it's OK. Removing 4 or 8 bytes from the task_struct is a decent win,
and an ifdef at the definition site (unavoidable) and at a single
initialisation site where there are lots of other similar ifdefs is pretty
minimal hurt.



In fact, looking through all those "= 0" and "= NULL" statements in
copy_process() makes one wonder whether we should be memsetting that guy to
zero then selectively copying things out of current, rather than the
present vice-versa.

A possibly-neat way of doing this would be to move all the task_struct fields which
are zeroed in copy_process() into a separate anonymous struct in
task_struct, then wipe only that in copy_process(). One would need to be
careful about the hand-arranged grouping which has been done in the
task_struct however.

-
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