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

[Stefano Stabellini]

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!


> 
> > 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 */
>