[PATCH V4 1/8] namespaces: assign each namespace instance a serial number

[Andy Lutomirski]

On Aug 20, 2014 8:12 PM, "Richard Guy Briggs" <rgb at redhat.com> wrote:
>
> Generate and assign a serial number per namespace instance since boot.
>
> Use a serial number per namespace (unique across one boot of one kernel)
> instead of the inode number (which is claimed to have had the right to change
> reserved and is not necessarily unique if there is more than one proc fs) to
> uniquely identify it per kernel boot.
>
> Signed-off-by: Richard Guy Briggs <rgb at redhat.com>
> ---
>  fs/mount.h                     |    1 +
>  fs/namespace.c                 |    1 +
>  include/linux/ipc_namespace.h  |    1 +
>  include/linux/nsproxy.h        |    8 ++++++++
>  include/linux/pid_namespace.h  |    1 +
>  include/linux/user_namespace.h |    1 +
>  include/linux/utsname.h        |    1 +
>  include/net/net_namespace.h    |    1 +
>  init/version.c                 |    1 +
>  ipc/msgutil.c                  |    1 +
>  ipc/namespace.c                |    2 ++
>  kernel/nsproxy.c               |   17 +++++++++++++++++
>  kernel/pid.c                   |    1 +
>  kernel/pid_namespace.c         |    2 ++
>  kernel/user.c                  |    1 +
>  kernel/user_namespace.c        |    2 ++
>  kernel/utsname.c               |    2 ++
>  net/core/net_namespace.c       |    8 +++++++-
>  18 files changed, 51 insertions(+), 1 deletions(-)
>
> diff --git a/fs/mount.h b/fs/mount.h
> index d55297f..c076f99 100644
> --- a/fs/mount.h
> +++ b/fs/mount.h
> @@ -5,6 +5,7 @@
>  struct mnt_namespace {
>         atomic_t                count;
>         unsigned int            proc_inum;
> +       long long       serial_num;
>         struct mount *  root;
>         struct list_head        list;
>         struct user_namespace   *user_ns;
> diff --git a/fs/namespace.c b/fs/namespace.c
> index 182bc41..9af49ff 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -2486,6 +2486,7 @@ static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns)
>                 kfree(new_ns);
>                 return ERR_PTR(ret);
>         }
> +       new_ns->serial_num = ns_serial();
>         new_ns->seq = atomic64_add_return(1, &mnt_ns_seq);
>         atomic_set(&new_ns->count, 1);
>         new_ns->root = NULL;
> diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
> index 35e7eca..8ccfb2d 100644
> --- a/include/linux/ipc_namespace.h
> +++ b/include/linux/ipc_namespace.h
> @@ -69,6 +69,7 @@ struct ipc_namespace {
>         struct user_namespace *user_ns;
>
>         unsigned int    proc_inum;
> +       long long       serial_num;
>  };
>
>  extern struct ipc_namespace init_ipc_ns;
> diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h
> index b4ec59d..8e5fe0d 100644
> --- a/include/linux/nsproxy.h
> +++ b/include/linux/nsproxy.h
> @@ -66,6 +66,14 @@ static inline struct nsproxy *task_nsproxy(struct task_struct *tsk)
>         return rcu_dereference(tsk->nsproxy);
>  }
>
> +long long ns_serial(void);
> +enum {
> +       NS_IPC_INIT_SN  = 1,
> +       NS_UTS_INIT_SN  = 2,
> +       NS_USER_INIT_SN = 3,
> +       NS_PID_INIT_SN  = 4,

Please add an extra value here for the first dynamic value...
> +/**
> + * ns_serial - compute a serial number for the namespace
> + *
> + * Compute a serial number for the namespace to uniquely identify it in
> + * audit records.
> + */
> +long long ns_serial(void)
> +{
> +       static atomic64_t serial = ATOMIC_INIT(4); /* reserved for IPC, UTS, user, PID */

...and use it here.

Also, does this work on all architectures?


--Andy