Re: [Xen-devel] [PATCH] xen: additionally restrict xenforeignmemory operations

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Stefano Stabellini [mailto:sstabellini@xxxxxxxxxx]
> Sent: 27 March 2017 18:46
> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> Cc: 'Stefano Stabellini' <sstabellini@xxxxxxxxxx>; qemu-devel@xxxxxxxxxx;
> xen-devel@xxxxxxxxxxxxxxxxxxxx; Anthony Perard
> <anthony.perard@xxxxxxxxxx>
> Subject: RE: [PATCH] xen: additionally restrict xenforeignmemory operations
> 
> On Mon, 27 Mar 2017, Paul Durrant wrote:
> > > -----Original Message-----
> > [snip]
> > >
> > > This is OK but the file is growing too entangled. What do you think of
> > > the following, which moves the if
> CONFIG_XEN_CTRL_INTERFACE_VERSION
> > > <
> > > 40701 at the top? This way we don't have to add yet another ifdef.
> > >
> >
> > Yes, this looks better and appears to DTRT. I assume you will just apply 
> > this
> version and don't want be to resubmit?
> 
> Actually, I would prefer if you could test it properly and resubmit the
> patch. Thanks!
> 

Ok, sure. I gave it a quick try yesterday but I'll send it as v2 later.

  Paul

> 
> >
> > > diff --git a/include/hw/xen/xen_common.h
> > > b/include/hw/xen/xen_common.h
> > > index 4f3bd35..624fb86 100644
> > > --- a/include/hw/xen/xen_common.h
> > > +++ b/include/hw/xen/xen_common.h
> > > @@ -27,6 +27,58 @@ extern xc_interface *xen_xc;
> > >   * We don't support Xen prior to 4.2.0.
> > >   */
> > >
> > > +/* Xen 4.2 through 4.6 */
> > > +#if CONFIG_XEN_CTRL_INTERFACE_VERSION < 40701
> > > +
> > > +typedef xc_interface xenforeignmemory_handle;
> > > +typedef xc_evtchn xenevtchn_handle;
> > > +typedef xc_gnttab xengnttab_handle;
> > > +
> > > +#define xenevtchn_open(l, f) xc_evtchn_open(l, f);
> > > +#define xenevtchn_close(h) xc_evtchn_close(h)
> > > +#define xenevtchn_fd(h) xc_evtchn_fd(h)
> > > +#define xenevtchn_pending(h) xc_evtchn_pending(h)
> > > +#define xenevtchn_notify(h, p) xc_evtchn_notify(h, p)
> > > +#define xenevtchn_bind_interdomain(h, d, p)
> > > xc_evtchn_bind_interdomain(h, d, p)
> > > +#define xenevtchn_unmask(h, p) xc_evtchn_unmask(h, p)
> > > +#define xenevtchn_unbind(h, p) xc_evtchn_unbind(h, p)
> > > +
> > > +#define xengnttab_open(l, f) xc_gnttab_open(l, f)
> > > +#define xengnttab_close(h) xc_gnttab_close(h)
> > > +#define xengnttab_set_max_grants(h, n)
> xc_gnttab_set_max_grants(h, n)
> > > +#define xengnttab_map_grant_ref(h, d, r, p)
> xc_gnttab_map_grant_ref(h,
> > > d, r, p)
> > > +#define xengnttab_unmap(h, a, n) xc_gnttab_munmap(h, a, n)
> > > +#define xengnttab_map_grant_refs(h, c, d, r, p) \
> > > +    xc_gnttab_map_grant_refs(h, c, d, r, p)
> > > +#define xengnttab_map_domain_grant_refs(h, c, d, r, p) \
> > > +    xc_gnttab_map_domain_grant_refs(h, c, d, r, p)
> > > +
> > > +#define xenforeignmemory_open(l, f) xen_xc
> > > +#define xenforeignmemory_close(h)
> > > +
> > > +static inline void *xenforeignmemory_map(xc_interface *h, uint32_t
> dom,
> > > +                                         int prot, size_t pages,
> > > +                                         const xen_pfn_t arr[/*pages*/],
> > > +                                         int err[/*pages*/])
> > > +{
> > > +    if (err)
> > > +        return xc_map_foreign_bulk(h, dom, prot, arr, err, pages);
> > > +    else
> > > +        return xc_map_foreign_pages(h, dom, prot, arr, pages);
> > > +}
> > > +
> > > +#define xenforeignmemory_unmap(h, p, s) munmap(p, s *
> XC_PAGE_SIZE)
> > > +
> > > +#else /* CONFIG_XEN_CTRL_INTERFACE_VERSION >= 40701 */
> > > +
> > > +#include <xenevtchn.h>
> > > +#include <xengnttab.h>
> > > +#include <xenforeignmemory.h>
> > > +
> > > +#endif
> > > +
> > > +extern xenforeignmemory_handle *xen_fmem;
> > > +
> > >  #if CONFIG_XEN_CTRL_INTERFACE_VERSION < 40900
> > >
> > >  typedef xc_interface xendevicemodel_handle;
> > > @@ -159,6 +211,13 @@ static inline int xendevicemodel_restrict(
> > >      return -1;
> > >  }
> > >
> > > +static inline int xenforeignmemory_restrict(
> > > +    xenforeignmemory_handle *fmem, domid_t domid)
> > > +{
> > > +    errno = ENOTTY;
> > > +    return -1;
> > > +}
> > > +
> > >  #else /* CONFIG_XEN_CTRL_INTERFACE_VERSION >= 40900 */
> > >
> > >  #include <xendevicemodel.h>
> > > @@ -215,69 +274,32 @@ static inline int xen_modified_memory(domid_t
> > > domid, uint64_t first_pfn,
> > >
> > >  static inline int xen_restrict(domid_t domid)
> > >  {
> > > -    int rc = xendevicemodel_restrict(xen_dmod, domid);
> > > +    int rc;
> > >
> > > -    trace_xen_domid_restrict(errno);
> > > +    /* Attempt to restrict devicemodel operations */
> > > +    rc = xendevicemodel_restrict(xen_dmod, domid);
> > > +    trace_xen_domid_restrict(rc ? errno : 0);
> > >
> > > -    if (errno == ENOTTY) {
> > > -        return 0;
> > > +    if (rc < 0) {
> > > +        /*
> > > +         * If errno is ENOTTY then restriction is not implemented so
> > > +         * there's no point in trying to restrict other types of
> > > +         * operation, but it should not be treated as a failure.
> > > +         */
> > > +        if (errno == ENOTTY) {
> > > +            return 0;
> > > +        }
> > > +
> > > +        return rc;
> > >      }
> > >
> > > -    return rc;
> > > -}
> > > -
> > > -/* Xen 4.2 through 4.6 */
> > > -#if CONFIG_XEN_CTRL_INTERFACE_VERSION < 40701
> > > -
> > > -typedef xc_interface xenforeignmemory_handle;
> > > -typedef xc_evtchn xenevtchn_handle;
> > > -typedef xc_gnttab xengnttab_handle;
> > > -
> > > -#define xenevtchn_open(l, f) xc_evtchn_open(l, f);
> > > -#define xenevtchn_close(h) xc_evtchn_close(h)
> > > -#define xenevtchn_fd(h) xc_evtchn_fd(h)
> > > -#define xenevtchn_pending(h) xc_evtchn_pending(h)
> > > -#define xenevtchn_notify(h, p) xc_evtchn_notify(h, p)
> > > -#define xenevtchn_bind_interdomain(h, d, p)
> > > xc_evtchn_bind_interdomain(h, d, p)
> > > -#define xenevtchn_unmask(h, p) xc_evtchn_unmask(h, p)
> > > -#define xenevtchn_unbind(h, p) xc_evtchn_unbind(h, p)
> > > -
> > > -#define xengnttab_open(l, f) xc_gnttab_open(l, f)
> > > -#define xengnttab_close(h) xc_gnttab_close(h)
> > > -#define xengnttab_set_max_grants(h, n) xc_gnttab_set_max_grants(h,
> n)
> > > -#define xengnttab_map_grant_ref(h, d, r, p)
> xc_gnttab_map_grant_ref(h,
> > > d, r, p)
> > > -#define xengnttab_unmap(h, a, n) xc_gnttab_munmap(h, a, n)
> > > -#define xengnttab_map_grant_refs(h, c, d, r, p) \
> > > -    xc_gnttab_map_grant_refs(h, c, d, r, p)
> > > -#define xengnttab_map_domain_grant_refs(h, c, d, r, p) \
> > > -    xc_gnttab_map_domain_grant_refs(h, c, d, r, p)
> > > -
> > > -#define xenforeignmemory_open(l, f) xen_xc
> > > -#define xenforeignmemory_close(h)
> > > +    /* Restrict foreignmemory operations */
> > > +    rc = xenforeignmemory_restrict(xen_fmem, domid);
> > > +    trace_xen_domid_restrict(rc ? errno : 0);
> > >
> > > -static inline void *xenforeignmemory_map(xc_interface *h, uint32_t
> dom,
> > > -                                         int prot, size_t pages,
> > > -                                         const xen_pfn_t arr[/*pages*/],
> > > -                                         int err[/*pages*/])
> > > -{
> > > -    if (err)
> > > -        return xc_map_foreign_bulk(h, dom, prot, arr, err, pages);
> > > -    else
> > > -        return xc_map_foreign_pages(h, dom, prot, arr, pages);
> > > +    return rc;
> > >  }
> > >
> > > -#define xenforeignmemory_unmap(h, p, s) munmap(p, s *
> XC_PAGE_SIZE)
> > > -
> > > -#else /* CONFIG_XEN_CTRL_INTERFACE_VERSION >= 40701 */
> > > -
> > > -#include <xenevtchn.h>
> > > -#include <xengnttab.h>
> > > -#include <xenforeignmemory.h>
> > > -
> > > -#endif
> > > -
> > > -extern xenforeignmemory_handle *xen_fmem;
> > > -
> > >  void destroy_hvm_domain(bool reboot);
> > >
> > >  /* shutdown/destroy current domain because of an error */
> >

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