Re: [AppArmor 39/45] AppArmor: Profile loading and manipulation, pathname matching

[david@lang.hm]

On Thu, 14 Jun 2007, Jack Stone wrote:

> david@lang.hm wrote:
> > On Sun, 10 Jun 2007, Pavel Machek wrote:
> > > But you have that regex in _user_ space, in a place where policy
> > > is loaded into kernel.
> >
> > then the kernel is going to have to call out to userspace every time a
> > file is created or renamed and the policy is going to be enforced
> > incorrectly until userspace finished labeling/relabeling whatever is
> > moved. building this sort of race condigion for security into the kernel
> > is highly questionable at best.
> >
> > > AA has regex parser in _kernel_ space, which is very wrong.
> >
> > see Linus' rants about why it's not automaticaly the best thing to move
> > functionality into userspace.
> >
> > remember that the files covered by an AA policy can change as files are
> > renamed. this isn't the case with SELinux so it doesn't have this sort
> > of problem.
>
> How about using the inotify interface on / to watch for file changes and
> updating the SELinux policies on the fly. This could be done from a
> userspace daemon and should require minimal SELinux changes.
>
> The only possible problems I can see are the (hopefully) small gap
> between the file change and updating the policy and the performance
> problems of watching the whole system for changes.

as was mentioned by someone else, if you rename a directory this can 
result in millions of files that need to be relabeled (or otherwise have 
the policy changed for them)

that can take a significant amount of time to do.

David Lang
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