Re: [Qemu-devel] [PATCH v3 2/6] seccomp: add obsolete argument to command line

["Daniel P. Berrange" <berrange@redhat.com>]

On Wed, Aug 02, 2017 at 01:33:56PM +0100, Daniel P. Berrange wrote:
> On Fri, Jul 28, 2017 at 02:10:36PM +0200, Eduardo Otubo wrote:
> > This patch introduces the argument [,obsolete=allow] to the `-sandbox on'
> > option. It allows Qemu to run safely on old system that still relies on
> > old system calls.
> > 
> > Signed-off-by: Eduardo Otubo <otubo@redhat.com>
> > ---
> >  include/sysemu/seccomp.h |  4 +++-
> >  qemu-options.hx          |  9 +++++++--
> >  qemu-seccomp.c           | 32 +++++++++++++++++++++++++++++++-
> >  vl.c                     | 16 +++++++++++++++-
> >  4 files changed, 56 insertions(+), 5 deletions(-)


> > @@ -1032,7 +1036,17 @@ static int parse_sandbox(void *opaque, QemuOpts *opts, Error **errp)
> >  {
> >      if (qemu_opt_get_bool(opts, "enable", false)) {
> >  #ifdef CONFIG_SECCOMP
> > -        if (seccomp_start() < 0) {
> > +        uint8_t seccomp_opts = 0x0000;
> > +        const char *value = NULL;
> > +
> > +        value = qemu_opt_get(opts, "obsolete");
> > +        if (value) {
> > +            if (strcmp(value, "allow") == 0) {
> > +                seccomp_opts |= OBSOLETE;
> > +            }
> > +        }
> 
> IIUC, the values will all be booleans, so we should just use
> 
>    if (qemu_opt_get_bool(opts, "obsolete", false))
>        seccomp_opts |= OBSOLETE;

Oh ignore this. I see from the next patch, we can't treat it as a boolean.

We should however explicitly look for 'value == deny', and then reject
all other values with an error message

> 
> > +
> > +        if (seccomp_start(seccomp_opts) < 0) {
> >              error_report("failed to install seccomp syscall filter "
> >                           "in the kernel");
> >              return -1;

Regards,
Daniel
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