[libcamera-devel] [PATCH] libcamera: process: Fail loudly on isolate

[Jacopo Mondi]

Hi Kieran,

On Fri, Jul 19, 2019 at 12:51:54PM +0100, Kieran Bingham wrote:
> Hi Jacopo,
>
> On 19/07/2019 09:05, Jacopo Mondi wrote:
> > Add an error debug message when disassociating part of a process
> > execution context using unshare fails.
> >
> > As this is currently used to isolate a child process which is
> > immediately terminated silently if unshare fails, add a debug printout
> > and propagate up the error code to make the failure more visible.
> >
>
> This sounds good to me.
>
> Have you added this because it has happened to you ?

Yes, isolate() fails on my device with -EPERM...
The only explanation I have is that CLONE_NEWUSER and CLONE_NEWNET
both requires CAP_SYS_ADMIN capability. I've just superficially looked
into this, but the printout helped me understand what was happening.

Thanks
  j

>
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
>
> > Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> > ---
> >  src/libcamera/process.cpp | 10 +++++++++-
> >  1 file changed, 9 insertions(+), 1 deletion(-)
> >
> > diff --git a/src/libcamera/process.cpp b/src/libcamera/process.cpp
> > index 6c41da219f05..ab716a9cd57f 100644
> > --- a/src/libcamera/process.cpp
> > +++ b/src/libcamera/process.cpp
> > @@ -306,7 +306,15 @@ void Process::closeAllFdsExcept(const std::vector<int> &fds)
> >
> >  int Process::isolate()
> >  {
> > -	return unshare(CLONE_NEWUSER | CLONE_NEWNET);
> > +	int ret = unshare(CLONE_NEWUSER | CLONE_NEWNET);
> > +	if (ret) {
> > +		ret = -errno;
> > +		LOG(Process, Error) << "Failed to unshare execution context: "
> > +				    << strerror(-ret);
> > +		return ret;
> > +	}
> > +
> > +	return 0;
> >  }
> >
> >  /**
> > --
> > 2.21.0
> >
> > _______________________________________________
> > libcamera-devel mailing list
> > libcamera-devel at lists.libcamera.org
> > https://lists.libcamera.org/listinfo/libcamera-devel
> >
>
> --
> Regards
> --
> Kieran
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