Quoting Eric W. Biederman (ebied...@xmission.com):
> Signed-off-by: "Eric W. Biederman" <ebied...@xmission.com>
Acked-by: Serge Hallyn <se...@hallyn.com>
> ---
> include/linux/user_namespace.h | 1 +
> kernel/cgroup.c | 15 +++++++++++++++
> kernel/user_namespace.c | 1 +
> 3 files changed, 17 insertions(+)
>
> diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
> index 367cf08ff63d..1a3a9cb93277 100644
> --- a/include/linux/user_namespace.h
> +++ b/include/linux/user_namespace.h
> @@ -27,6 +27,7 @@ enum ucounts {
> UCOUNT_PID_NAMESPACES,
> UCOUNT_UTS_NAMESPACES,
> UCOUNT_IPC_NAMESPACES,
> + UCOUNT_CGROUP_NAMESPACES,
> UCOUNT_COUNTS,
> };
>
> diff --git a/kernel/cgroup.c b/kernel/cgroup.c
> index 86cb5c6e8932..240eec43390b 100644
> --- a/kernel/cgroup.c
> +++ b/kernel/cgroup.c
> @@ -6260,6 +6260,16 @@ void cgroup_sk_free(struct sock_cgroup_data *skcd)
>
> /* cgroup namespaces */
>
> +static bool inc_cgroup_namespaces(struct user_namespace *ns)
> +{
> + return inc_ucount(ns, UCOUNT_CGROUP_NAMESPACES);
> +}
> +
> +static void dec_cgroup_namespaces(struct user_namespace *ns)
> +{
> + dec_ucount(ns, UCOUNT_CGROUP_NAMESPACES);
> +}
> +
> static struct cgroup_namespace *alloc_cgroup_ns(void)
> {
> struct cgroup_namespace *new_ns;
> @@ -6281,6 +6291,7 @@ static struct cgroup_namespace *alloc_cgroup_ns(void)
> void free_cgroup_ns(struct cgroup_namespace *ns)
> {
> put_css_set(ns->root_cset);
> + dec_cgroup_namespaces(ns->user_ns);
> put_user_ns(ns->user_ns);
> ns_free_inum(&ns->ns);
> kfree(ns);
> @@ -6305,6 +6316,9 @@ struct cgroup_namespace *copy_cgroup_ns(unsigned long
> flags,
> if (!ns_capable(user_ns, CAP_SYS_ADMIN))
> return ERR_PTR(-EPERM);
>
> + if (!inc_cgroup_namespaces(user_ns))
> + return ERR_PTR(-ENFILE);
> +
> mutex_lock(&cgroup_mutex);
> spin_lock_bh(&css_set_lock);
>
> @@ -6317,6 +6331,7 @@ struct cgroup_namespace *copy_cgroup_ns(unsigned long
> flags,
> new_ns = alloc_cgroup_ns();
> if (IS_ERR(new_ns)) {
> put_css_set(cset);
> + dec_cgroup_namespaces(user_ns);
> return new_ns;
> }
>
> diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
> index 060d3e099f87..1cf074cb47e2 100644
> --- a/kernel/user_namespace.c
> +++ b/kernel/user_namespace.c
> @@ -80,6 +80,7 @@ static struct ctl_table userns_table[] = {
> UCOUNT_ENTRY("max_pid_namespaces"),
> UCOUNT_ENTRY("max_uts_namespaces"),
> UCOUNT_ENTRY("max_ipc_namespaces"),
> + UCOUNT_ENTRY("max_cgroup_namespaces"),
> { }
> };
> #endif /* CONFIG_SYSCTL */
> --
> 2.8.3
