Quoting Andrew Morton ([email protected]):
> On Mon, 6 Aug 2007 15:31:12 -0500 "Serge E. Hallyn" <[email protected]> wrote:
>
> > Quoting Alexey Dobriyan ([email protected]):
> > > 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.
(Hmm, I'm replying at the point in the email I'm replying to. Is what
I'm doing in this current email ok - i.e the one you replied to looked
like pure top-posting - or do you actually want pure bottom posting?)
> > 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 <[email protected]>
> > > ---
> > >
> > > 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.
Then how about making it depend on CONFIG_SECURITY_SELINUX? It's the
only LSM actually using that field right now. (As more come along, we
can use a hidden CONFIG_SECURITY_ATTRS or somesuch bool select'ed by
LSMs which need it)
Using CONFIG_SECURITY means that if you compile with SECURITY=n, you get
the capability module but no task->security. If you compile with
SECURITY=y but no modules, you get the dummy module and a
task->security field!
> 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.
thanks,
-serge
-
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