Quoting Eric W. Biederman (ebied...@xmission.com):
> Signed-off-by: "Eric W. Biederman" <ebied...@xmission.com>
Acked-by: Serge Hallyn <se...@hallyn.com>
Thanks, Eric.
> ---
> fs/namespace.c | 19 ++++++++++++++++++-
> include/linux/user_namespace.h | 1 +
> kernel/user_namespace.c | 1 +
> 3 files changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/fs/namespace.c b/fs/namespace.c
> index aabe8e397fc3..3942ae6c34f5 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -2718,9 +2718,20 @@ dput_out:
> return retval;
> }
>
> +static bool inc_mnt_namespaces(struct user_namespace *ns)
> +{
> + return inc_ucount(ns, UCOUNT_MNT_NAMESPACES);
> +}
> +
> +static void dec_mnt_namespaces(struct user_namespace *ns)
> +{
> + dec_ucount(ns, UCOUNT_MNT_NAMESPACES);
> +}
> +
> static void free_mnt_ns(struct mnt_namespace *ns)
> {
> ns_free_inum(&ns->ns);
> + dec_mnt_namespaces(ns->user_ns);
> put_user_ns(ns->user_ns);
> kfree(ns);
> }
> @@ -2739,12 +2750,18 @@ static struct mnt_namespace *alloc_mnt_ns(struct
> user_namespace *user_ns)
> struct mnt_namespace *new_ns;
> int ret;
>
> + if (!inc_mnt_namespaces(user_ns))
> + return ERR_PTR(-ENFILE);
> +
> new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL);
> - if (!new_ns)
> + if (!new_ns) {
> + dec_mnt_namespaces(user_ns);
> return ERR_PTR(-ENOMEM);
> + }
> ret = ns_alloc_inum(&new_ns->ns);
> if (ret) {
> kfree(new_ns);
> + dec_mnt_namespaces(user_ns);
> return ERR_PTR(ret);
> }
> new_ns->ns.ops = &mntns_operations;
> diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
> index f86afa536baf..ee0e9d7b2e67 100644
> --- a/include/linux/user_namespace.h
> +++ b/include/linux/user_namespace.h
> @@ -28,6 +28,7 @@ enum ucounts {
> UCOUNT_UTS_NAMESPACES,
> UCOUNT_IPC_NAMESPACES,
> UCOUNT_NET_NAMESPACES,
> + UCOUNT_MNT_NAMESPACES,
> UCOUNT_CGROUP_NAMESPACES,
> UCOUNT_COUNTS,
> };
> diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
> index e326ca722ae0..f6702d84afab 100644
> --- a/kernel/user_namespace.c
> +++ b/kernel/user_namespace.c
> @@ -81,6 +81,7 @@ static struct ctl_table userns_table[] = {
> UCOUNT_ENTRY("max_uts_namespaces"),
> UCOUNT_ENTRY("max_ipc_namespaces"),
> UCOUNT_ENTRY("max_net_namespaces"),
> + UCOUNT_ENTRY("max_mnt_namespaces"),
> UCOUNT_ENTRY("max_cgroup_namespaces"),
> { }
> };
> --
> 2.8.3
