[RFC][v8][PATCH 7/10]: Check invalid clone flags

[Sukadev Bhattiprolu <sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>]

Subject: [RFC][v8][PATCH 7/10]: Check invalid clone flags

As pointed out by Oren Laadan, we want to ensure that unused bits in the
clone-flags remain unused and available for future. To ensure this, define
a mask of clone-flags and check the flags in the clone() system calls.

Changelog[v8]:
	- New patch in set

Signed-off-by: Sukadev Bhattiprolu <sukadev-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>

---
 include/linux/sched.h |   10 ++++++++++
 kernel/fork.c         |    3 +++
 2 files changed, 13 insertions(+)

Index: linux-2.6/include/linux/sched.h
===================================================================
--- linux-2.6.orig/include/linux/sched.h	2009-10-02 18:53:55.000000000 -0700
+++ linux-2.6/include/linux/sched.h	2009-10-02 19:58:21.000000000 -0700
@@ -29,6 +29,16 @@
 #define CLONE_NEWNET		0x40000000	/* New network namespace */
 #define CLONE_IO		0x80000000	/* Clone io context */
 
+#define VALID_CLONE_FLAGS	(CSIGNAL | CLONE_VM | CLONE_FS | CLONE_FILES |\
+				 CLONE_SIGHAND | CLONE_PTRACE | CLONE_VFORK  |\
+				 CLONE_PARENT | CLONE_THREAD | CLONE_NEWNS   |\
+				 CLONE_SYSVSEM | CLONE_SETTLS                |\
+				 CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID  |\
+				 CLONE_DETACHED | CLONE_UNTRACED             |\
+				 CLONE_CHILD_SETTID | CLONE_STOPPED          |\
+				 CLONE_NEWUTS | CLONE_NEWIPC | CLONE_NEWUSER |\
+				 CLONE_NEWPID | CLONE_NEWNET| CLONE_IO)
+
 /*
  * Scheduling policies
  */
Index: linux-2.6/kernel/fork.c
===================================================================
--- linux-2.6.orig/kernel/fork.c	2009-10-02 19:00:08.000000000 -0700
+++ linux-2.6/kernel/fork.c	2009-10-02 19:57:36.000000000 -0700
@@ -942,6 +942,9 @@ static struct task_struct *copy_process(
 	struct task_struct *p;
 	int cgroup_callbacks_done = 0;
 
+	if (clone_flags & ~VALID_CLONE_FLAGS)
+		return ERR_PTR(-EINVAL);
+
 	if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
 		return ERR_PTR(-EINVAL);