Re: [PATCH v3 0/3] Send audit/procinfo/cgroup data in socket-levelcontrol message

[Jan Kaluža]

On 09/04/2013 04:58 PM, Richard Guy Briggs wrote:
> On Wed, Sep 04, 2013 at 12:42:26AM -0700, Eric W. Biederman wrote:
> > Jan Kaluza <jkaluza@xxxxxxxxxx> writes:
> > > Hi,
> > >
> > > this patchset against net-next (applies also to linux-next) adds 3 new types
> > > of "Socket"-level control message (SCM_AUDIT, SCM_PROCINFO and SCM_CGROUP).
> > >
> > > Server-like processes in many cases need credentials and other
> > > metadata of the peer, to decide if the calling process is allowed to
> > > request a specific action, or the server just wants to log away this
> > > type of information for auditing tasks.
> > >
> > > The current practice to retrieve such process metadata is to look that
> > > information up in procfs with the $PID received over SCM_CREDENTIALS.
> > > This is sufficient for long-running tasks, but introduces a race which
> > > cannot be worked around for short-living processes; the calling
> > > process and all the information in /proc/$PID/ is gone before the
> > > receiver of the socket message can look it up.
> >
> > > Changes introduced in this patchset can also increase performance
> > > of such server-like processes, because current way of opening and
> > > parsing /proc/$PID/* files is much more expensive than receiving these
> > > metadata using SCM.
> >
> > Can I just say ick, blech, barf, gag.
>
> /me hands ebiederman an air sickness bag.
>
> > You don't require this information to be passed.  You are asking people
> > to suport a lot of new code for the forseeable future.  The only advantage
> > appears to be for short lived racy processes that don't even bother to
> > make certain their message was acknowleged before exiting.
> >
> > You sent this during the merge window which is the time for code
> > integration and testing not new code.
>
> This is an RFC.  How is this important?
>
> > By my count you have overflowed cb in struct sk_buff and are stomping on
> > _skb_refdest.
>
> For patch1/3 I count 56/48, then for patch3 I get 48/48.  Jan, you might
> do the conversion to a pointer in patch1/3 to avoid bisect breakage.

Yes, this is valid point. I will do the conversion in patch1. Thanks all 
for reviewing and pointing that out.

Jan Kaluza

> > If you are going to go crazy and pass things is there a reason you do
> > not add a patch to pass the bsd SCM_CREDS?  That information seems more
> > relevant in a security context and for making security decisions than
> > about half the information you are passing.
> >
> > Eric
>
> - RGB
>
> --
> Richard Guy Briggs <rbriggs@xxxxxxxxxx>
> Senior Software Engineer
> Kernel Security
> AMER ENG Base Operating Systems
> Remote, Ottawa, Canada
> Voice: +1.647.777.2635
> Internal: (81) 32635
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