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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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