tools/libs/evtchn: Add support for restricting a handle

Implement support for restricting evtchn handles to a particular domain
on Linux by calling the IOCTL_EVTCHN_RESTRICT_DOMID ioctl (support added
in Linux v4.8).

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Release-acked-by: Julien Grall <julien.grall@linaro.org>

tools/include/xen-sys/Linux/evtchn.h

@@ -85,4 +85,19 @@ struct ioctl_evtchn_notify {
 #define IOCTL_EVTCHN_RESET				\
 	_IOC(_IOC_NONE, 'E', 5, 0)
 
+/*
+ * Restrict this file descriptor so that it can only be used to bind
+ * new interdomain events from one domain.
+ *
+ * Once a file descriptor has been restricted it cannot be
+ * de-restricted, and must be closed and re-opened.  Event channels
+ * which were bound before restricting remain bound afterwards, and
+ * can be notified as usual.
+ */
+#define IOCTL_EVTCHN_RESTRICT_DOMID			\
+	_IOC(_IOC_NONE, 'E', 6, sizeof(struct ioctl_evtchn_restrict_domid))
+struct ioctl_evtchn_restrict_domid {
+	domid_t domid;
+};
+
 #endif /* __LINUX_PUBLIC_EVTCHN_H__ */

tools/libs/evtchn/Makefile

@@ -2,7 +2,7 @@ XEN_ROOT = $(CURDIR)/../../..
 include $(XEN_ROOT)/tools/Rules.mk
 
 MAJOR    = 1
-MINOR    = 0
+MINOR    = 1
 SHLIB_LDFLAGS += -Wl,--version-script=libxenevtchn.map
 
 CFLAGS   += -Werror -Wmissing-prototypes

tools/libs/evtchn/core.c

@@ -61,6 +61,11 @@ int xenevtchn_close(xenevtchn_handle *xce)
     return rc;
 }
 
+int xenevtchn_restrict(xenevtchn_handle *xce, domid_t domid)
+{
+    return osdep_evtchn_restrict(xce, domid);
+}
+
 /*
  * Local variables:
  * mode: C

tools/libs/evtchn/freebsd.c

@@ -47,6 +47,12 @@ int osdep_evtchn_close(xenevtchn_handle *xce)
     return close(xce->fd);
 }
 
+int osdep_evtchn_restrict(xenevtchn_handle *xce, domid_t domid)
+{
+    errno = -EOPNOTSUPP;
+    return -1;
+}
+
 int xenevtchn_fd(xenevtchn_handle *xce)
 {
     return xce->fd;

tools/libs/evtchn/include/xenevtchn.h

@@ -151,6 +151,16 @@ xenevtchn_pending(xenevtchn_handle *xce);
  */
 int xenevtchn_unmask(xenevtchn_handle *xce, evtchn_port_t port);
 
+/**
+ * This function restricts the use of this handle to the specified
+ * domain.
+ *
+ * @parm xce handle to the open evtchn interface
+ * @parm domid the domain id
+ * @return 0 on success, -1 on failure with errno set appropriately.
+ */
+int xenevtchn_restrict(xenevtchn_handle *xce, domid_t domid);
+
 #endif
 
 /*

tools/libs/evtchn/libxenevtchn.map

@@ -17,3 +17,7 @@ VERS_1.0 {
 		xenevtchn_pending;
 	local: *; /* Do not expose anything by default */
 };
+VERS_1.1 {
+	global:
+		xenevtchn_restrict;
+} VERS_1.0;

tools/libs/evtchn/linux.c

@@ -21,9 +21,11 @@
 #include <fcntl.h>
 #include <unistd.h>
 #include <stdlib.h>
+#include <stdint.h>
 
 #include <sys/ioctl.h>
 
+#include <xen/xen.h>
 #include <xen/sys/evtchn.h>
 
 #include "private.h"
@@ -49,6 +51,13 @@ int osdep_evtchn_close(xenevtchn_handle *xce)
     return close(xce->fd);
 }
 
+int osdep_evtchn_restrict(xenevtchn_handle *xce, domid_t domid)
+{
+    struct ioctl_evtchn_restrict_domid restrict_domid = { domid };
+
+    return ioctl(xce->fd, IOCTL_EVTCHN_RESTRICT_DOMID, &restrict_domid);
+}
+
 int xenevtchn_fd(xenevtchn_handle *xce)
 {
     return xce->fd;

tools/libs/evtchn/minios.c

@@ -82,6 +82,12 @@ int osdep_evtchn_close(xenevtchn_handle *xce)
     return close(xce->fd);
 }
 
+int osdep_evtchn_restrict(xenevtchn_handle *xce, domid_t domid)
+{
+    errno = -EOPNOTSUPP;
+    return -1;
+}
+
 void minios_evtchn_close_fd(int fd)
 {
     struct evtchn_port_info *port_info, *tmp;

tools/libs/evtchn/netbsd.c

@@ -47,6 +47,12 @@ int osdep_evtchn_close(xenevtchn_handle *xce)
     return close(xce->fd);
 }
 
+int osdep_evtchn_restrict(xenevtchn_handle *xce, domid_t domid)
+{
+    errno = -EOPNOTSUPP;
+    return -1;
+}
+
 int xenevtchn_fd(xenevtchn_handle *xce)
 {
     return xce->fd;

tools/libs/evtchn/private.h

@@ -4,6 +4,8 @@
 #include <xentoollog.h>
 #include <xenevtchn.h>
 
+#include <xen/xen.h>
+
 struct xenevtchn_handle {
     xentoollog_logger *logger, *logger_tofree;
     int fd;
@@ -11,6 +13,7 @@ struct xenevtchn_handle {
 
 int osdep_evtchn_open(xenevtchn_handle *xce);
 int osdep_evtchn_close(xenevtchn_handle *xce);
+int osdep_evtchn_restrict(xenevtchn_handle *xce, domid_t domid);
 
 #endif
 

tools/libs/evtchn/solaris.c

@@ -50,6 +50,12 @@ int osdep_evtchn_close(xenevtchn_handle *xce)
     return close(xce->fd);
 }
 
+int osdep_evtchn_restrict(xenevtchn_handle *xce, domid_t domid)
+{
+    errno = -EOPNOTSUPP;
+    return -1;
+}
+
 int xenevtchn_fd(xenevtchn_handle *xce)
 {
     return xce->fd;

tools/libvchan/init.c

@@ -40,6 +40,7 @@
 #include <fcntl.h>
 
 #include <xenstore.h>
+#include <xen/xen.h>
 #include <xen/sys/evtchn.h>
 #include <xen/sys/gntalloc.h>
 #include <xen/sys/gntdev.h>

tools/libvchan/libxenvchan.h

@@ -43,6 +43,7 @@
  */
 
 #include <xen/io/libxenvchan.h>
+#include <xen/xen.h>
 #include <xen/sys/evtchn.h>
 #include <xenevtchn.h>
 #include <xengnttab.h>