// SPDX-License-Identifier: GPL-2.0-or-later
/* L2TP subsystem debugfs
 *
 * Copyright (c) 2010 Katalix Systems Ltd
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/socket.h>
#include <linux/hash.h>
#include <linux/l2tp.h>
#include <linux/in.h>
#include <linux/etherdevice.h>
#include <linux/spinlock.h>
#include <linux/debugfs.h>
#include <net/sock.h>
#include <net/ip.h>
#include <net/icmp.h>
#include <net/udp.h>
#include <net/inet_common.h>
#include <net/inet_hashtables.h>
#include <net/tcp_states.h>
#include <net/protocol.h>
#include <net/xfrm.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>

#include "l2tp_core.h"

static struct dentry *rootdir;

struct l2tp_dfs_seq_data {
        struct net      *net;
        netns_tracker   ns_tracker;
        unsigned long tkey;             /* lookup key of current tunnel */
        unsigned long skey;             /* lookup key of current session */
        struct l2tp_tunnel *tunnel;
        struct l2tp_session *session;   /* NULL means get next tunnel */
};

static void l2tp_dfs_next_tunnel(struct l2tp_dfs_seq_data *pd)
{
        /* Drop reference taken during previous invocation */
        if (pd->tunnel)
                l2tp_tunnel_put(pd->tunnel);

        pd->tunnel = l2tp_tunnel_get_next(pd->net, &pd->tkey);
        pd->tkey++;
}

static void l2tp_dfs_next_session(struct l2tp_dfs_seq_data *pd)
{
        /* Drop reference taken during previous invocation */
        if (pd->session)
                l2tp_session_put(pd->session);

        pd->session = l2tp_session_get_next(pd->net, pd->tunnel->sock,
                                            pd->tunnel->version,
                                            pd->tunnel->tunnel_id, &pd->skey);
        pd->skey++;

        if (!pd->session) {
                pd->skey = 0;
                l2tp_dfs_next_tunnel(pd);
        }
}

static void *l2tp_dfs_seq_start(struct seq_file *m, loff_t *offs)
{
        struct l2tp_dfs_seq_data *pd = SEQ_START_TOKEN;
        loff_t pos = *offs;

        if (!pos)
                goto out;

        if (WARN_ON(!m->private)) {
                pd = NULL;
                goto out;
        }
        pd = m->private;

        if (!pd->tunnel)
                l2tp_dfs_next_tunnel(pd);
        else
                l2tp_dfs_next_session(pd);

        /* NULL tunnel and session indicates end of list */
        if (!pd->tunnel && !pd->session)
                pd = NULL;

out:
        return pd;
}

static void *l2tp_dfs_seq_next(struct seq_file *m, void *v, loff_t *pos)
{
        (*pos)++;
        return NULL;
}

static void l2tp_dfs_seq_stop(struct seq_file *p, void *v)
{
        struct l2tp_dfs_seq_data *pd = v;

        if (!pd || pd == SEQ_START_TOKEN)
                return;

        /* Drop reference taken by last invocation of l2tp_dfs_next_session()
         * or l2tp_dfs_next_tunnel().
         */
        if (pd->session) {
                l2tp_session_put(pd->session);
                pd->session = NULL;
        }
        if (pd->tunnel) {
                l2tp_tunnel_put(pd->tunnel);
                pd->tunnel = NULL;
        }
}

static void l2tp_dfs_seq_tunnel_show(struct seq_file *m, void *v)
{
        struct l2tp_tunnel *tunnel = v;
        struct l2tp_session *session;
        int session_count = 0;

        rcu_read_lock_bh();
        list_for_each_entry_rcu(session, &tunnel->session_list, list) {
                /* Session ID of zero is a dummy/reserved value used by pppol2tp */
                if (session->session_id == 0)
                        continue;

                session_count++;
        }
        rcu_read_unlock_bh();

        seq_printf(m, "\nTUNNEL %u peer %u", tunnel->tunnel_id, tunnel->peer_tunnel_id);
        if (tunnel->sock) {
                struct inet_sock *inet = inet_sk(tunnel->sock);

#if IS_ENABLED(CONFIG_IPV6)
                if (tunnel->sock->sk_family == AF_INET6) {
                        const struct ipv6_pinfo *np = inet6_sk(tunnel->sock);

                        seq_printf(m, " from %pI6c to %pI6c\n",
                                   &np->saddr, &tunnel->sock->sk_v6_daddr);
                }
#endif
                if (tunnel->sock->sk_family == AF_INET)
                        seq_printf(m, " from %pI4 to %pI4\n",
                                   &inet->inet_saddr, &inet->inet_daddr);

                if (tunnel->encap == L2TP_ENCAPTYPE_UDP)
                        seq_printf(m, " source port %hu, dest port %hu\n",
                                   ntohs(inet->inet_sport), ntohs(inet->inet_dport));
        }
        seq_printf(m, " L2TPv%d, %s\n", tunnel->version,
                   tunnel->encap == L2TP_ENCAPTYPE_UDP ? "UDP" :
                   tunnel->encap == L2TP_ENCAPTYPE_IP ? "IP" :
                   "");
        seq_printf(m, " %d sessions, refcnt %d/%d\n", session_count,
                   tunnel->sock ? refcount_read(&tunnel->sock->sk_refcnt) : 0,
                   refcount_read(&tunnel->ref_count));
        seq_printf(m, " %08x tx %ld/%ld/%ld rx %ld/%ld/%ld\n",
                   0,
                   atomic_long_read(&tunnel->stats.tx_packets),
                   atomic_long_read(&tunnel->stats.tx_bytes),
                   atomic_long_read(&tunnel->stats.tx_errors),
                   atomic_long_read(&tunnel->stats.rx_packets),
                   atomic_long_read(&tunnel->stats.rx_bytes),
                   atomic_long_read(&tunnel->stats.rx_errors));
}

static void l2tp_dfs_seq_session_show(struct seq_file *m, void *v)
{
        struct l2tp_session *session = v;

        seq_printf(m, "  SESSION %u, peer %u, %s\n", session->session_id,
                   session->peer_session_id,
                   session->pwtype == L2TP_PWTYPE_ETH ? "ETH" :
                   session->pwtype == L2TP_PWTYPE_PPP ? "PPP" :
                   "");
        if (session->send_seq || session->recv_seq)
                seq_printf(m, "   nr %u, ns %u\n", session->nr, session->ns);
        seq_printf(m, "   refcnt %d\n", refcount_read(&session->ref_count));
        seq_printf(m, "   config 0/0/%c/%c/-/%s %08x %u\n",
                   session->recv_seq ? 'R' : '-',
                   session->send_seq ? 'S' : '-',
                   session->lns_mode ? "LNS" : "LAC",
                   0,
                   jiffies_to_msecs(session->reorder_timeout));
        seq_printf(m, "   offset 0 l2specific %hu/%d\n",
                   session->l2specific_type, l2tp_get_l2specific_len(session));
        if (session->cookie_len) {
                seq_printf(m, "   cookie %02x%02x%02x%02x",
                           session->cookie[0], session->cookie[1],
                           session->cookie[2], session->cookie[3]);
                if (session->cookie_len == 8)
                        seq_printf(m, "%02x%02x%02x%02x",
                                   session->cookie[4], session->cookie[5],
                                   session->cookie[6], session->cookie[7]);
                seq_puts(m, "\n");
        }
        if (session->peer_cookie_len) {
                seq_printf(m, "   peer cookie %02x%02x%02x%02x",
                           session->peer_cookie[0], session->peer_cookie[1],
                           session->peer_cookie[2], session->peer_cookie[3]);
                if (session->peer_cookie_len == 8)
                        seq_printf(m, "%02x%02x%02x%02x",
                                   session->peer_cookie[4], session->peer_cookie[5],
                                   session->peer_cookie[6], session->peer_cookie[7]);
                seq_puts(m, "\n");
        }

        seq_printf(m, "   %u/%u tx %ld/%ld/%ld rx %ld/%ld/%ld\n",
                   session->nr, session->ns,
                   atomic_long_read(&session->stats.tx_packets),
                   atomic_long_read(&session->stats.tx_bytes),
                   atomic_long_read(&session->stats.tx_errors),
                   atomic_long_read(&session->stats.rx_packets),
                   atomic_long_read(&session->stats.rx_bytes),
                   atomic_long_read(&session->stats.rx_errors));

        if (session->show)
                session->show(m, session);
}

static int l2tp_dfs_seq_show(struct seq_file *m, void *v)
{
        struct l2tp_dfs_seq_data *pd = v;

        /* display header on line 1 */
        if (v == SEQ_START_TOKEN) {
                seq_puts(m, "TUNNEL ID, peer ID from IP to IP\n");
                seq_puts(m, " L2TPv2/L2TPv3, UDP/IP\n");
                seq_puts(m, " sessions session-count, refcnt refcnt/sk->refcnt\n");
                seq_puts(m, " debug tx-pkts/bytes/errs rx-pkts/bytes/errs\n");
                seq_puts(m, "  SESSION ID, peer ID, PWTYPE\n");
                seq_puts(m, "   refcnt cnt\n");
                seq_puts(m, "   offset OFFSET l2specific TYPE/LEN\n");
                seq_puts(m, "   [ cookie ]\n");
                seq_puts(m, "   [ peer cookie ]\n");
                seq_puts(m, "   config mtu/mru/rcvseq/sendseq/dataseq/lns debug reorderto\n");
                seq_puts(m, "   nr/ns tx-pkts/bytes/errs rx-pkts/bytes/errs\n");
                goto out;
        }

        if (!pd->session)
                l2tp_dfs_seq_tunnel_show(m, pd->tunnel);
        else
                l2tp_dfs_seq_session_show(m, pd->session);

out:
        return 0;
}

static const struct seq_operations l2tp_dfs_seq_ops = {
        .start          = l2tp_dfs_seq_start,
        .next           = l2tp_dfs_seq_next,
        .stop           = l2tp_dfs_seq_stop,
        .show           = l2tp_dfs_seq_show,
};

static int l2tp_dfs_seq_open(struct inode *inode, struct file *file)
{
        struct l2tp_dfs_seq_data *pd;
        struct seq_file *seq;
        int rc = -ENOMEM;

        pd = kzalloc_obj(*pd);
        if (!pd)
                goto out;

        /* Derive the network namespace from the pid opening the
         * file.
         */
        pd->net = get_net_ns_by_pid(current->pid);
        if (IS_ERR(pd->net)) {
                rc = PTR_ERR(pd->net);
                goto err_free_pd;
        }
        netns_tracker_alloc(pd->net, &pd->ns_tracker, GFP_KERNEL);
        rc = seq_open(file, &l2tp_dfs_seq_ops);
        if (rc)
                goto err_free_net;

        seq = file->private_data;
        seq->private = pd;

out:
        return rc;

err_free_net:
        put_net_track(pd->net, &pd->ns_tracker);
err_free_pd:
        kfree(pd);
        goto out;
}

static int l2tp_dfs_seq_release(struct inode *inode, struct file *file)
{
        struct l2tp_dfs_seq_data *pd;
        struct seq_file *seq;

        seq = file->private_data;
        pd = seq->private;
        if (pd->net)
                put_net_track(pd->net, &pd->ns_tracker);
        kfree(pd);
        seq_release(inode, file);

        return 0;
}

static const struct file_operations l2tp_dfs_fops = {
        .owner          = THIS_MODULE,
        .open           = l2tp_dfs_seq_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = l2tp_dfs_seq_release,
};

static int __init l2tp_debugfs_init(void)
{
        rootdir = debugfs_create_dir("l2tp", NULL);

        debugfs_create_file("tunnels", 0600, rootdir, NULL, &l2tp_dfs_fops);

        pr_info("L2TP debugfs support\n");

        return 0;
}

static void __exit l2tp_debugfs_exit(void)
{
        debugfs_remove_recursive(rootdir);
}

module_init(l2tp_debugfs_init);
module_exit(l2tp_debugfs_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
MODULE_DESCRIPTION("L2TP debugfs driver");
MODULE_VERSION("1.0");