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Subject[v13][PATCH 06/12] Check invalid clone flags

From: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Subject: [v13][PATCH 06/12] 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[v9]:
- Include the unused clone-flag (CLONE_UNUSED) to VALID_CLONE_FLAGS
to avoid breaking any applications that may have set it. IOW, this
patch/check only applies to clone-flags bits 33 and higher.

Changelog[v8]:
- New patch in set

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
---
include/linux/sched.h | 12 ++++++++++++
kernel/fork.c | 3 +++
2 files changed, 15 insertions(+), 0 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 75e6e60..a4d2c23 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -29,6 +29,18 @@
#define CLONE_NEWNET 0x40000000 /* New network namespace */
#define CLONE_IO 0x80000000 /* Clone io context */

+#define CLONE_UNUSED 0x00001000 /* Can be reused ? */
+
+#define VALID_CLONE_FLAGS (CSIGNAL | CLONE_VM | CLONE_FS | CLONE_FILES |\
+ CLONE_SIGHAND | CLONE_UNUSED | 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
*/
diff --git a/kernel/fork.c b/kernel/fork.c
index 72c76a1..317adcf 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -982,6 +982,9 @@ static struct task_struct *copy_process(unsigned long clone_flags,
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);

--
1.6.0.4


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