From 8c4d15d5b824fd02bd6909f6d254828732f3bb7b Mon Sep 17 00:00:00 2001
From: Justus Winter <4winter@informatik.uni-hamburg.de>
Date: Tue, 4 Nov 2014 18:46:42 +0100
Subject: kern: provide notifications about new tasks

These notifications are sent to the port registered via
`register_new_task_notification' and provide a robust parental
relation between tasks to a userspace server.

* Makefrag.am: Add task_notify.defs.
* include/mach/gnumach.defs: Add register_new_task_notification.
* include/mach/task_notify.defs: New file.
* kern/task.c (new_task_notification): New variable.
(task_create): Send new task notifications.
(register_new_task_notification): Add server function.
* kern/task_notify.cli: New file.
---
 kern/task.c          | 33 +++++++++++++++++++++++++++++++++
 kern/task_notify.cli |  7 +++++++
 2 files changed, 40 insertions(+)
 create mode 100644 kern/task_notify.cli

(limited to 'kern')

diff --git a/kern/task.c b/kern/task.c
index 44963c6..a11fb8e 100644
--- a/kern/task.c
+++ b/kern/task.c
@@ -50,12 +50,16 @@
 #include <kern/sched_prim.h>	/* for thread_wakeup */
 #include <kern/ipc_tt.h>
 #include <kern/syscall_emulation.h>
+#include <kern/task_notify.user.h>
 #include <vm/vm_kern.h>		/* for kernel_map, ipc_kernel_map */
 #include <machine/machspl.h>	/* for splsched */
 
 task_t	kernel_task = TASK_NULL;
 struct kmem_cache task_cache;
 
+/* Where to send notifications about newly created tasks.  */
+ipc_port_t new_task_notification = NULL;
+
 void task_init(void)
 {
 	kmem_cache_init(&task_cache, "task", sizeof(struct task), 0,
@@ -169,6 +173,14 @@ kern_return_t task_create(
 
 	snprintf (new_task->name, sizeof new_task->name, "%p", new_task);
 
+	if (new_task_notification != NULL) {
+		task_reference (new_task);
+		task_reference (parent_task);
+		mach_notify_new_task (new_task_notification,
+				      convert_task_to_port (new_task),
+				      convert_task_to_port (parent_task));
+	}
+
 	ipc_task_enable(new_task);
 
 	*child_task = new_task;
@@ -1249,3 +1261,24 @@ task_ras_control(
 #endif /* FAST_TAS */
     return ret;
 }
+
+/*
+ *	register_new_task_notification
+ *
+ *	Register a port to which a notification about newly created
+ *	tasks are sent.
+ */
+kern_return_t
+register_new_task_notification(
+	const host_t host,
+	ipc_port_t notification)
+{
+	if (host == HOST_NULL)
+		return KERN_INVALID_HOST;
+
+	if (new_task_notification != NULL)
+		return KERN_NO_ACCESS;
+
+	new_task_notification = notification;
+	return KERN_SUCCESS;
+}
diff --git a/kern/task_notify.cli b/kern/task_notify.cli
new file mode 100644
index 0000000..c6c85d9
--- /dev/null
+++ b/kern/task_notify.cli
@@ -0,0 +1,7 @@
+/* XXX */
+
+/* This is a client presentation file.  */
+
+#define KERNEL_USER 1
+
+#include <mach/task_notify.defs>
-- 
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