/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * cls_cgroup.h                 Control Group Classifier
 *
 * Authors:     Thomas Graf <tgraf@suug.ch>
 */

#ifndef _NET_CLS_CGROUP_H
#define _NET_CLS_CGROUP_H

#include <linux/cgroup.h>
#include <linux/hardirq.h>
#include <linux/rcupdate.h>
#include <net/sock.h>
#include <net/inet_sock.h>

#ifdef CONFIG_CGROUP_NET_CLASSID
struct cgroup_cls_state {
        struct cgroup_subsys_state css;
        u32 classid;
};

struct cgroup_cls_state *task_cls_state(struct task_struct *p);

static inline u32 task_cls_classid(struct task_struct *p)
{
        u32 classid;

        if (in_interrupt())
                return 0;

        rcu_read_lock();
        classid = container_of(task_css(p, net_cls_cgrp_id),
                               struct cgroup_cls_state, css)->classid;
        rcu_read_unlock();

        return classid;
}

static inline void sock_update_classid(struct sock_cgroup_data *skcd)
{
        u32 classid;

        classid = task_cls_classid(current);
        sock_cgroup_set_classid(skcd, classid);
}

static inline u32 __task_get_classid(struct task_struct *task)
{
        return task_cls_state(task)->classid;
}

static inline u32 task_get_classid(const struct sk_buff *skb)
{
        u32 classid = __task_get_classid(current);

        /* Due to the nature of the classifier it is required to ignore all
         * packets originating from softirq context as accessing `current'
         * would lead to false results.
         *
         * This test assumes that all callers of dev_queue_xmit() explicitly
         * disable bh. Knowing this, it is possible to detect softirq based
         * calls by looking at the number of nested bh disable calls because
         * softirqs always disables bh.
         */
        if (softirq_count()) {
                struct sock *sk = skb_to_full_sk(skb);

                /* If there is an sock_cgroup_classid we'll use that. */
                if (!sk || !sk_fullsock(sk))
                        return 0;

                classid = sock_cgroup_classid(&sk->sk_cgrp_data);
        }

        return classid;
}
#else /* !CONFIG_CGROUP_NET_CLASSID */
static inline void sock_update_classid(struct sock_cgroup_data *skcd)
{
}

static inline u32 task_get_classid(const struct sk_buff *skb)
{
        return 0;
}
#endif /* CONFIG_CGROUP_NET_CLASSID */
#endif  /* _NET_CLS_CGROUP_H */