kernel: userspace: add k_object_is_valid()

This adds a function k_object_is_valid() to check if a kernel
object exists, of certain type, and has been initialized.
This replaces the same (or very similar) code that has been
copied from kernel into the network subsystem.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>

include/zephyr/sys/kobject.h

@@ -192,6 +192,19 @@ __syscall void k_object_release(const void *object);
  */
 void k_object_access_all_grant(const void *object);
 
+/**
+ * Check if a kernel object is of certain type and is valid.
+ *
+ * This checks if the kernel object exists, of certain type,
+ * and has been initialized.
+ *
+ * @param obj Address of the kernel object
+ * @param otype Object type (use K_OBJ_ANY for ignoring type checking)
+ * @return True if kernel object (@a obj) exists, of certain type, and
+ *         has been initialized. False otherwise.
+ */
+bool k_object_is_valid(const void *obj, enum k_objects otype);
+
 #else
 /* LCOV_EXCL_START */
 #define K_THREAD_ACCESS_GRANT(thread, ...)
@@ -236,6 +249,15 @@ static inline void k_object_access_all_grant(const void *object)
 {
 	ARG_UNUSED(object);
 }
+
+static inline bool k_object_is_valid(const void *obj, enum k_objects otype)
+{
+	ARG_UNUSED(obj);
+	ARG_UNUSED(otype);
+
+	return true;
+}
+
 /* LCOV_EXCL_STOP */
 #endif /* !CONFIG_USERSPACE */
 

kernel/userspace_handler.c

@@ -7,8 +7,11 @@
 #include <zephyr/kernel.h>
 #include <zephyr/syscall_handler.h>
 #include <zephyr/kernel_structs.h>
+#include <zephyr/toolchain.h>
 
-static struct z_object *validate_any_object(const void *obj)
+static struct z_object *validate_kernel_object(const void *obj,
+					       enum k_objects otype,
+					       enum _obj_init_check init)
 {
 	struct z_object *ko;
 	int ret;
@@ -18,10 +21,10 @@ static struct z_object *validate_any_object(const void *obj)
 	/* This can be any kernel object and it doesn't have to be
 	 * initialized
 	 */
-	ret = z_object_validate(ko, K_OBJ_ANY, _OBJ_INIT_ANY);
+	ret = z_object_validate(ko, otype, init);
 	if (ret != 0) {
 #ifdef CONFIG_LOG
-		z_dump_object_error(ret, obj, ko, K_OBJ_ANY);
+		z_dump_object_error(ret, obj, ko, otype);
 #endif
 		return NULL;
 	}
@@ -29,6 +32,20 @@ static struct z_object *validate_any_object(const void *obj)
 	return ko;
 }
 
+static ALWAYS_INLINE struct z_object *validate_any_object(const void *obj)
+{
+	return validate_kernel_object(obj, K_OBJ_ANY, _OBJ_INIT_ANY);
+}
+
+bool k_object_is_valid(const void *obj, enum k_objects otype)
+{
+	struct z_object *ko;
+
+	ko = validate_kernel_object(obj, otype, _OBJ_INIT_TRUE);
+
+	return (ko != NULL);
+}
+
 /* Normally these would be included in userspace.c, but the way
  * syscall_dispatch.c declares weak handlers results in build errors if these
  * are located in userspace.c. Just put in a separate file.

subsys/net/ip/net_if.c

@@ -152,19 +152,13 @@ struct net_if *z_impl_net_if_get_by_index(int index)
 struct net_if *z_vrfy_net_if_get_by_index(int index)
 {
 	struct net_if *iface;
-	struct z_object *zo;
-	int ret;
 
 	iface = net_if_get_by_index(index);
 	if (!iface) {
 		return NULL;
 	}
 
-	zo = z_object_find(iface);
-
-	ret = z_object_validate(zo, K_OBJ_NET_IF, _OBJ_INIT_TRUE);
-	if (ret != 0) {
-		z_dump_object_error(ret, iface, zo, K_OBJ_NET_IF);
+	if (!k_object_is_valid(iface, K_OBJ_NET_IF)) {
 		return NULL;
 	}
 

subsys/net/lib/sockets/sockets.c

@@ -78,14 +78,7 @@ static inline void *get_sock_vtable(int sock,
 
 #ifdef CONFIG_USERSPACE
 	if (ctx != NULL && z_is_in_user_syscall()) {
-		struct z_object *zo;
-		int ret;
-
-		zo = z_object_find(ctx);
-		ret = z_object_validate(zo, K_OBJ_NET_SOCKET, _OBJ_INIT_TRUE);
-
-		if (ret != 0) {
-			z_dump_object_error(ret, ctx, zo, K_OBJ_NET_SOCKET);
+		if (!k_object_is_valid(ctx, K_OBJ_NET_SOCKET)) {
 			/* Invalidate the context, the caller doesn't have
 			 * sufficient permission or there was some other
 			 * problem with the net socket object

tests/kernel/mem_protect/mem_protect/src/kobject.c

@@ -1034,18 +1034,11 @@ ZTEST(mem_protect_kobj, test_create_new_invalid_prio_thread_from_user)
 /* Function to init thread's stack objects */
 static void thread_stack_init_objects(void *p1, void *p2, void *p3)
 {
-	int ret;
-	struct z_object *ko;
-
 	/* check that thread is initialized when running */
-	ko = z_object_find(&child_thread);
-	ret = z_object_validate(ko, K_OBJ_ANY, _OBJ_INIT_TRUE);
-	zassert_equal(ret, _OBJ_INIT_TRUE);
+	zassert_true(k_object_is_valid(&child_thread, K_OBJ_ANY));
 
 	/* check that stack is initialized when running */
-	ko = z_object_find(child_stack);
-	ret = z_object_validate(ko, K_OBJ_ANY, _OBJ_INIT_TRUE);
-	zassert_equal(ret, _OBJ_INIT_TRUE);
+	zassert_true(k_object_is_valid(child_stack, K_OBJ_ANY));
 }
 
 /**