Re: [PATCH 12/19] CacheFiles: Permit a process's create SID to be overridden

[Karl MacMillan <kmacmillan@mentalrootkit.com>]

Stephen Smalley wrote:
> On Tue, 2006-11-14 at 16:19 -0500, James Morris wrote:
> > On Tue, 14 Nov 2006, David Howells wrote:
> >
> > > +static u32 selinux_set_fscreate_secid(u32 secid)
> > > +{
> > > +	struct task_security_struct *tsec = current->security;
> > > +	u32 oldsid = tsec->create_sid;
> > > +
> > > +	tsec->create_sid = secid;
> > > +	return oldsid;
> > > +}
> > The ability to set this needs to be mediated via MAC policy.
> >
> > See selinux_setprocattr()
>
> That's different - selinux_set_fscreate_secid() is for internal use by a
> kernel module that wishes to temporarily assume a particular fscreate
> SID, whereas selinux_setprocattr() handles userspace writes
> to /proc/self/attr nodes.  Imposing a permission check here makes no
> sense.

Since that discussion last week I have been thinking about this and I 
have to say I agree with Steve. This should be a kernel only mechanism 
for impersonating another SID - controlling the setting of process 
attributes shouldn't be restricted as this will only lead to 
inconsistencies in those attributes.

Karl
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