Re: [PATCH V2 05/10] x86/pks: Add PKS kernel API

Ira Weiny
2020-11-03T18:42:22Z

On Tue, Nov 03, 2020 at 07:14:07PM +0100, Greg KH wrote:
> On Tue, Nov 03, 2020 at 09:53:36AM -0800, Ira Weiny wrote:
> > On Tue, Nov 03, 2020 at 07:50:24AM +0100, Greg KH wrote:
> > > On Mon, Nov 02, 2020 at 12:53:15PM -0800, ira.weiny@intel.com wrote:
> > > > From: Fenghua Yu <fenghua.yu@intel.com>
> > > >
> >
> > [snip]
> >
> > > > diff --git a/include/linux/pkeys.h b/include/linux/pkeys.h
> > > > index 2955ba976048..0959a4c0ca64 100644
> > > > --- a/include/linux/pkeys.h
> > > > +++ b/include/linux/pkeys.h
> > > > @@ -50,4 +50,28 @@ static inline void copy_init_pkru_to_fpregs(void)
> > > >
> > > > #endif /* ! CONFIG_ARCH_HAS_PKEYS */
> > > >
> > > > +#define PKS_FLAG_EXCLUSIVE 0x00
> > > > +
> > > > +#ifndef CONFIG_ARCH_HAS_SUPERVISOR_PKEYS
> > > > +static inline int pks_key_alloc(const char * const pkey_user, int flags)
> > > > +{
> > > > + return -EOPNOTSUPP;
> > > > +}
> > > > +static inline void pks_key_free(int pkey)
> > > > +{
> > > > +}
> > > > +static inline void pks_mk_noaccess(int pkey)
> > > > +{
> > > > + WARN_ON_ONCE(1);
> > >
> > > So for panic-on-warn systems, this is ok to reboot the box?
> >
> > I would not expect this to reboot the box no. But it is a violation of the API
> > contract. If pky_key_alloc() returns an error calling any of the other
> > functions is an error.
> >
> > >
> > > Are you sure, that feels odd...
> >
> > It does feel odd and downright wrong... But there are a lot of WARN_ON_ONCE's
> > out there to catch this type of internal programming error. Is panic-on-warn
> > commonly used?
>
> Yes it is, and we are trying to recover from that as it is something
> that you should recover from. Properly handle the error and move on.

Sorry, I did not know that... Ok I'll look at the series because I probably
have others I need to change.

Thanks,
Ira