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/pid_namespace.c | 22 ++++++++++++++++++----
> kernel/user_namespace.c | 1 +
> 3 files changed, 20 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
> index f74a0facc696..47733637741a 100644
> --- a/include/linux/user_namespace.h
> +++ b/include/linux/user_namespace.h
> @@ -24,6 +24,7 @@ struct uid_gid_map { /* 64 bytes -- 1 cache line */
>
> enum ucounts {
> UCOUNT_USER_NAMESPACES,
> + UCOUNT_PID_NAMESPACES,
> UCOUNT_COUNTS,
> };
>
> diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
> index a65ba137fd15..049cc14ae37a 100644
> --- a/kernel/pid_namespace.c
> +++ b/kernel/pid_namespace.c
> @@ -79,6 +79,16 @@ static void proc_cleanup_work(struct work_struct *work)
> /* MAX_PID_NS_LEVEL is needed for limiting size of 'struct pid' */
> #define MAX_PID_NS_LEVEL 32
>
> +static bool inc_pid_namespaces(struct user_namespace *ns)
> +{
> + return inc_ucount(ns, UCOUNT_PID_NAMESPACES);
> +}
> +
> +static void dec_pid_namespaces(struct user_namespace *ns)
> +{
> + dec_ucount(ns, UCOUNT_PID_NAMESPACES);
> +}
> +
> static struct pid_namespace *create_pid_namespace(struct user_namespace
> *user_ns,
> struct pid_namespace *parent_pid_ns)
> {
> @@ -87,15 +97,16 @@ static struct pid_namespace *create_pid_namespace(struct
> user_namespace *user_ns
> int i;
> int err;
>
> - if (level > MAX_PID_NS_LEVEL) {
> - err = -EINVAL;
> + err = -EINVAL;
> + if (level > MAX_PID_NS_LEVEL)
> + goto out;
> + if (!inc_pid_namespaces(user_ns))
> goto out;
> - }
>
> err = -ENOMEM;
> ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
> if (ns == NULL)
> - goto out;
> + goto out_dec;
>
> ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
> if (!ns->pidmap[0].page)
> @@ -129,6 +140,8 @@ out_free_map:
> kfree(ns->pidmap[0].page);
> out_free:
> kmem_cache_free(pid_ns_cachep, ns);
> +out_dec:
> + dec_pid_namespaces(user_ns);
> out:
> return ERR_PTR(err);
> }
> @@ -146,6 +159,7 @@ static void destroy_pid_namespace(struct pid_namespace
> *ns)
> ns_free_inum(&ns->ns);
> for (i = 0; i < PIDMAP_ENTRIES; i++)
> kfree(ns->pidmap[i].page);
> + dec_pid_namespaces(ns->user_ns);
> put_user_ns(ns->user_ns);
> call_rcu(&ns->rcu, delayed_free_pidns);
> }
> diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
> index 728d7e4995ff..02a03ead7afc 100644
> --- a/kernel/user_namespace.c
> +++ b/kernel/user_namespace.c
> @@ -77,6 +77,7 @@ static int count_max = COUNT_MAX;
> }
> static struct ctl_table userns_table[] = {
> UCOUNT_ENTRY("max_user_namespaces"),
> + UCOUNT_ENTRY("max_pid_namespaces"),
> { }
> };
> #endif /* CONFIG_SYSCTL */
> --
> 2.8.3
