xsm: expose context of event channel peers

This hypercall allows a domain to identify the security context of a
domain that it is communicating with using the interdomain event
channel that it is using for the communication. This can be used to
augment Xen's security permissions with intra-domain security checks.

Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Committed-by: Keir Fraser <keir@xen.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/xen/include/xen/event.h b/xen/include/xen/event.h
index 22fc6a3f3d..11a639adff 100644
--- a/xen/include/xen/event.h
+++ b/xen/include/xen/event.h
@@ -70,6 +70,16 @@ int guest_enabled_event(struct vcpu *v, uint32_t virq);
 /* Notify remote end of a Xen-attached event channel.*/
 void notify_via_xen_event_channel(struct domain *ld, int lport);
 
+/* Internal event channel object accessors */
+#define bucket_from_port(d,p) \
+    ((d)->evtchn[(p)/EVTCHNS_PER_BUCKET])
+#define port_is_valid(d,p)    \
+    (((p) >= 0) && ((p) < MAX_EVTCHNS(d)) && \
+     (bucket_from_port(d,p) != NULL))
+#define evtchn_from_port(d,p) \
+    (&(bucket_from_port(d,p))[(p)&(EVTCHNS_PER_BUCKET-1)])
+
+
 /* Wait on a Xen-attached event channel. */
 #define wait_on_xen_event_channel(port, condition)                      \
     do {                                                                \