Re: [v12][PATCH 6/9] Check invalid clone flags

[Sukadev Bhattiprolu]

Cc: LKML

Sukadev Bhattiprolu [sukadev@xxxxxxxxxxxxxxxxxx] wrote:
| 
| Subject: [v12][PATCH 6/9] 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@xxxxxxxxxxxxxxxxxx>
| Acked-by: Oren Laadan <orenl@xxxxxxxxxxxxxxx>
| ---
|  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 c8a06de..11f77ed 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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