RE: [PATCH] DSPBRIDGE: Validate node handle from user

[Ameya Palande <ameya.palande@nokia.com>]

On Tue, 2010-02-09 at 18:52 +0100, ext Ramos Falcon, Ernesto wrote:
> 
> >-----Original Message-----
> >From: Ameya Palande [mailto:ameya.palande@nokia.com]
> >Sent: Tuesday, February 09, 2010 11:32 AM
> >To: Ramos Falcon, Ernesto
> >Cc: linux-omap@vger.kernel.org; Contreras Felipe (Nokia-D/Helsinki); Doyu
> >Hiroshi (Nokia-D/Helsinki)
> >Subject: Re: [PATCH] DSPBRIDGE: Validate node handle from user
> >
> >Hi Ernesto,
> >
> >On Tue, 2010-02-09 at 18:08 +0100, ext Ramos Falcon, Ernesto wrote:
> >> From 8310b586b025b0703c3951560849c4ea0250b6e1 Mon Sep 17 00:00:00 2001
> >> From: Ernesto Ramos <ernesto@ti.com>
> >> Date: Fri, 29 Jan 2010 16:21:59 -0600
> >> Subject: [PATCH] DSPBRIDGE: Validate node handle from user.
> >>
> >> Add checks to validate the node handles received from user.
> >>
> >> Signed-off-by: Ernesto Ramos <ernesto@ti.com>
> >> ---
> >>  drivers/dsp/bridge/pmgr/wcd.c  |   91 ++++++++++++++++++++-
> >>  drivers/dsp/bridge/rmgr/node.c |  174 +++++++++++++---------------------
> >-----
> >>  2 files changed, 146 insertions(+), 119 deletions(-)
> >>
> >> diff --git a/drivers/dsp/bridge/pmgr/wcd.c
> >b/drivers/dsp/bridge/pmgr/wcd.c
> >> index 74654dc..2e6eeb0 100644
> >> --- a/drivers/dsp/bridge/pmgr/wcd.c
> >> +++ b/drivers/dsp/bridge/pmgr/wcd.c
> >> @@ -1066,6 +1066,24 @@ u32 PROCWRAP_Stop(union Trapped_Args *args, void
> >*pr_ctxt)
> >>         return retVal;
> >>  }
> >>
> >> +bool validate_node_handle(struct NODE_OBJECT *hNode, void *pr_ctxt)
> >> +{
> >> +       bool retVal = false;
> >> +       struct PROCESS_CONTEXT *pCtxt = pr_ctxt;
> >> +       struct NODE_RES_OBJECT *pNode = pCtxt->pNodeList;
> >> +
> >> +       if (hNode == (struct NODE_OBJECT *) DSP_HGPPNODE)
> >> +               retVal = true;
> >> +
> >> +       while (pNode && !retVal) {
> >> +               if (hNode == pNode->hNode)
> >
> >If you have several nodes allocated by user space, then what you are
> >validating here is for any node! Is that ok?
> >
> >This validation and design itself doesn't look good to me. If we don't
> >want to trust user space, then instead of checking the node handle in
> >every function it is better to store all user space specific date inside
> >pr_context and use it from there.
> >
> 
> The user can launch several nodes, how are we going to know which node handle to use?
> I think we may need to receive at least one index or id to the node handle.

Yes, I guess thats the correct way! We need to maintain how many nodes
are allocated for a user process, and just make sure that this id /
index is <= number of allocated nodes.

Cheers,
Ameya.