tools/xenstored: Rename dom0_domid to store_domid

The dom0_domid variable is misnamed and conflates purposes.  If we have
xenstored running in a Linux domain that is not dom0, this variable
controls the lookup of /proc/xen/xsd_kva and the event channel.

Rename to store_domid to better show its purpose.

One implication of this change is that the xenstore domain is not
privileged by virtue of considering store_domid as privileged.

domain_is_unprivileged() removes the dom0_domid/store_domid check, so
xenstore domain is no longer considered privileged.

onearg_domain() is updated to return EINVAL for store_domid or priv_domid
to maintain the ability to call XS_RESUME.

xenbus_master_domid() is removed with store_domid being used instead.

Add a description of the -m/--master-domid options while
doing this.

Signed-off-by: Jason Andryuk <jason.andryuk@amd.com>
Reviewed-by: Juergen Gross <jgross@suse.com>

tools/xenstored/core.c

@@ -2539,7 +2539,10 @@ static void usage(void)
 "                          allowed timeout candidates are:\n"
 "                          watch-event: time a watch-event is kept pending\n"
 "  -K, --keep-orphans      don't delete nodes owned by a domain when the\n"
-"                          domain is deleted (this is a security risk!)\n");
+"                          domain is deleted (this is a security risk!)\n"
+"  -m, --master-domid      specify the domid of the domain where xenstored\n"
+"                          is running.  defaults to 0\n"
+);
 }
 
 
@@ -2567,7 +2570,7 @@ static struct option options[] = {
 #endif
 	{ NULL, 0, NULL, 0 } };
 
-int dom0_domid = DOMID_INVALID;
+int store_domid = DOMID_INVALID;
 int dom0_event = 0;
 int priv_domid = DOMID_INVALID;
 domid_t stub_domid = DOMID_INVALID;
@@ -2736,7 +2739,7 @@ int main(int argc, char *argv[])
 			dom0_event = get_optval_uint(optarg);
 			break;
 		case 'm':
-			dom0_domid = get_optval_uint(optarg);
+			store_domid = get_optval_uint(optarg);
 			break;
 		case 'p':
 			priv_domid = get_optval_uint(optarg);

tools/xenstored/core.h

@@ -365,7 +365,7 @@ do {						\
 		trace("tdb: " __VA_ARGS__);	\
 } while (0)
 
-extern int dom0_domid;
+extern int store_domid;
 extern int dom0_event;
 extern int priv_domid;
 extern domid_t stub_domid;
@@ -382,11 +382,9 @@ uint64_t get_now_msec(void);
 void *xenbus_map(void);
 void unmap_xenbus(void *interface);
 
-static inline int xenbus_master_domid(void) { return dom0_domid; }
-
 static inline bool domid_is_unprivileged(unsigned int domid)
 {
-	return domid != dom0_domid && domid != priv_domid;
+	return domid != priv_domid;
 }
 
 static inline bool domain_is_unprivileged(const struct connection *conn)

tools/xenstored/domain.c

@@ -509,7 +509,7 @@ static const struct interface_funcs domain_funcs = {
 
 static void *map_interface(domid_t domid)
 {
-	if (domid == xenbus_master_domid())
+	if (domid == store_domid)
 		return xenbus_map();
 
 #ifdef __MINIOS__
@@ -524,7 +524,7 @@ static void *map_interface(domid_t domid)
 
 static void unmap_interface(domid_t domid, void *interface)
 {
-	if (domid == xenbus_master_domid())
+	if (domid == store_domid)
 		unmap_xenbus(interface);
 	else if (domid != stub_domid)
 		xengnttab_unmap(*xgt_handle, interface, 1);
@@ -1158,7 +1158,7 @@ static struct domain *onearg_domain(struct connection *conn,
 		return ERR_PTR(-EINVAL);
 
 	domid = atoi(domid_str);
-	if (domid == dom0_domid)
+	if (domid == store_domid || domid == priv_domid)
 		return ERR_PTR(-EINVAL);
 
 	return find_connected_domain(domid);
@@ -1381,14 +1381,14 @@ void init_domains(void)
 			 * have 1 domain.  stubdom there will be dom0 and dom1,
 			 * so this will take the second for stubdom.
 			 */
-			dom0_domid = domid;
+			store_domid = domid;
 		}
 	}
 
-	if (dom0_domid == DOMID_INVALID)
-		dom0_domid = priv_domid;
+	if (store_domid == DOMID_INVALID)
+		store_domid = priv_domid;
 
-	if (dom0_domid == DOMID_INVALID)
+	if (store_domid == DOMID_INVALID)
 		barf("Could not determine xenstore domid\n");
 
 	/*

tools/xenstored/posix.c

@@ -174,7 +174,7 @@ static evtchn_port_t get_xenbus_evtchn(void)
  */
 evtchn_port_t get_domain_evtchn(unsigned int domid)
 {
-	if (domid == xenbus_master_domid())
+	if (domid == store_domid)
 		return get_xenbus_evtchn();
 
 	return 0;
@@ -280,7 +280,7 @@ static void accept_connection(int sock)
 	conn = new_connection(&socket_funcs);
 	if (conn) {
 		conn->fd = fd;
-		conn->id = dom0_domid;
+		conn->id = store_domid;
 	} else
 		close(fd);
 }