text: // 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;
  	int tunnel_idx;			/* current tunnel */
  	int session_idx;		/* index of session within current tunnel */
  	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_dec_refcount(pd->tunnel);
  
  	pd->tunnel = l2tp_tunnel_get_nth(pd->net, pd->tunnel_idx);
  	pd->tunnel_idx++;
  }
  
  static void l2tp_dfs_next_session(struct l2tp_dfs_seq_data *pd)
  {
  	/* Drop reference taken during previous invocation */
  	if (pd->session)
  		l2tp_session_dec_refcount(pd->session);
  
  	pd->session = l2tp_session_get_nth(pd->tunnel, pd->session_idx);
  	pd->session_idx++;
  
  	if (pd->session == NULL) {
  		pd->session_idx = 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;
  
  	BUG_ON(m->private == NULL);
  	pd = m->private;
  
  	if (pd->tunnel == NULL)
  		l2tp_dfs_next_tunnel(pd);
  	else
  		l2tp_dfs_next_session(pd);
  
  	/* NULL tunnel and session indicates end of list */
  	if ((pd->tunnel == NULL) && (pd->session == NULL))
  		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_dec_refcount(pd->session);
  		pd->session = NULL;
  	}
  	if (pd->tunnel) {
  		l2tp_tunnel_dec_refcount(pd->tunnel);
  		pd->tunnel = NULL;
  	}
  }
  
  static void l2tp_dfs_seq_tunnel_show(struct seq_file *m, void *v)
  {
  	struct l2tp_tunnel *tunnel = v;
  	int session_count = 0;
  	int hash;
  	struct hlist_node *walk;
  	struct hlist_node *tmp;
  
  	read_lock_bh(&tunnel->hlist_lock);
  	for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
  		hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
  			struct l2tp_session *session;
  
  			session = hlist_entry(walk, struct l2tp_session, hlist);
  			if (session->session_id == 0)
  				continue;
  
  			session_count++;
  		}
  	}
  	read_unlock_bh(&tunnel->hlist_lock);
  
  	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);
  		} else
  #endif
  		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 rx %ld/%ld/%ld rx %ld/%ld/%ld\n",
  		   tunnel->debug,
  		   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 %hu, ns %hu\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",
  		   session->debug,
  		   jiffies_to_msecs(session->reorder_timeout));
  	seq_printf(m, "   offset 0 l2specific %hu/%hu\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_printf(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_printf(m, "\n");
  	}
  
  	seq_printf(m, "   %hu/%hu 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 != NULL)
  		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(sizeof(*pd), GFP_KERNEL);
  	if (pd == NULL)
  		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;
  	}
  
  	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(pd->net);
  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(pd->net);
  	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");
  