l2tp_ppp.c 46.6 KB
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/*****************************************************************************
 * Linux PPP over L2TP (PPPoX/PPPoL2TP) Sockets
 *
 * PPPoX    --- Generic PPP encapsulation socket family
 * PPPoL2TP --- PPP over L2TP (RFC 2661)
 *
 * Version:	2.0.0
 *
 * Authors:	James Chapman (jchapman@katalix.com)
 *
 * Based on original work by Martijn van Oosterhout <kleptog@svana.org>
 *
 * License:
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 *
 */

/* This driver handles only L2TP data frames; control frames are handled by a
 * userspace application.
 *
 * To send data in an L2TP session, userspace opens a PPPoL2TP socket and
 * attaches it to a bound UDP socket with local tunnel_id / session_id and
 * peer tunnel_id / session_id set. Data can then be sent or received using
 * regular socket sendmsg() / recvmsg() calls. Kernel parameters of the socket
 * can be read or modified using ioctl() or [gs]etsockopt() calls.
 *
 * When a PPPoL2TP socket is connected with local and peer session_id values
 * zero, the socket is treated as a special tunnel management socket.
 *
 * Here's example userspace code to create a socket for sending/receiving data
 * over an L2TP session:-
 *
 *	struct sockaddr_pppol2tp sax;
 *	int fd;
 *	int session_fd;
 *
 *	fd = socket(AF_PPPOX, SOCK_DGRAM, PX_PROTO_OL2TP);
 *
 *	sax.sa_family = AF_PPPOX;
 *	sax.sa_protocol = PX_PROTO_OL2TP;
 *	sax.pppol2tp.fd = tunnel_fd;	// bound UDP socket
 *	sax.pppol2tp.addr.sin_addr.s_addr = addr->sin_addr.s_addr;
 *	sax.pppol2tp.addr.sin_port = addr->sin_port;
 *	sax.pppol2tp.addr.sin_family = AF_INET;
 *	sax.pppol2tp.s_tunnel  = tunnel_id;
 *	sax.pppol2tp.s_session = session_id;
 *	sax.pppol2tp.d_tunnel  = peer_tunnel_id;
 *	sax.pppol2tp.d_session = peer_session_id;
 *
 *	session_fd = connect(fd, (struct sockaddr *)&sax, sizeof(sax));
 *
 * A pppd plugin that allows PPP traffic to be carried over L2TP using
 * this driver is available from the OpenL2TP project at
 * http://openl2tp.sourceforge.net.
 */

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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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#include <linux/module.h>
#include <linux/string.h>
#include <linux/list.h>
#include <linux/uaccess.h>

#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/kthread.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/jiffies.h>

#include <linux/netdevice.h>
#include <linux/net.h>
#include <linux/inetdevice.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/ip.h>
#include <linux/udp.h>
#include <linux/if_pppox.h>
#include <linux/if_pppol2tp.h>
#include <net/sock.h>
#include <linux/ppp_channel.h>
#include <linux/ppp_defs.h>
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#include <linux/ppp-ioctl.h>
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#include <linux/file.h>
#include <linux/hash.h>
#include <linux/sort.h>
#include <linux/proc_fs.h>
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#include <linux/l2tp.h>
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#include <linux/nsproxy.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>
#include <net/dst.h>
#include <net/ip.h>
#include <net/udp.h>
#include <net/xfrm.h>
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#include <net/inet_common.h>
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#include <asm/byteorder.h>
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#include <linux/atomic.h>
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#include "l2tp_core.h"

#define PPPOL2TP_DRV_VERSION	"V2.0"

/* Space for UDP, L2TP and PPP headers */
#define PPPOL2TP_HEADER_OVERHEAD	40

/* Number of bytes to build transmit L2TP headers.
 * Unfortunately the size is different depending on whether sequence numbers
 * are enabled.
 */
#define PPPOL2TP_L2TP_HDR_SIZE_SEQ		10
#define PPPOL2TP_L2TP_HDR_SIZE_NOSEQ		6

/* Private data of each session. This data lives at the end of struct
 * l2tp_session, referenced via session->priv[].
 */
struct pppol2tp_session {
	int			owner;		/* pid that opened the socket */

	struct sock		*sock;		/* Pointer to the session
						 * PPPoX socket */
	struct sock		*tunnel_sock;	/* Pointer to the tunnel UDP
						 * socket */
	int			flags;		/* accessed by PPPIOCGFLAGS.
						 * Unused. */
};

static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb);

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static const struct ppp_channel_ops pppol2tp_chan_ops = {
	.start_xmit =  pppol2tp_xmit,
};

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static const struct proto_ops pppol2tp_ops;

/* Helpers to obtain tunnel/session contexts from sockets.
 */
static inline struct l2tp_session *pppol2tp_sock_to_session(struct sock *sk)
{
	struct l2tp_session *session;

	if (sk == NULL)
		return NULL;

	sock_hold(sk);
	session = (struct l2tp_session *)(sk->sk_user_data);
	if (session == NULL) {
		sock_put(sk);
		goto out;
	}

	BUG_ON(session->magic != L2TP_SESSION_MAGIC);

out:
	return session;
}

/*****************************************************************************
 * Receive data handling
 *****************************************************************************/

static int pppol2tp_recv_payload_hook(struct sk_buff *skb)
{
	/* Skip PPP header, if present.	 In testing, Microsoft L2TP clients
	 * don't send the PPP header (PPP header compression enabled), but
	 * other clients can include the header. So we cope with both cases
	 * here. The PPP header is always FF03 when using L2TP.
	 *
	 * Note that skb->data[] isn't dereferenced from a u16 ptr here since
	 * the field may be unaligned.
	 */
	if (!pskb_may_pull(skb, 2))
		return 1;

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	if ((skb->data[0] == PPP_ALLSTATIONS) && (skb->data[1] == PPP_UI))
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		skb_pull(skb, 2);

	return 0;
}

/* Receive message. This is the recvmsg for the PPPoL2TP socket.
 */
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static int pppol2tp_recvmsg(struct socket *sock, struct msghdr *msg,
			    size_t len, int flags)
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{
	int err;
	struct sk_buff *skb;
	struct sock *sk = sock->sk;

	err = -EIO;
	if (sk->sk_state & PPPOX_BOUND)
		goto end;

	err = 0;
	skb = skb_recv_datagram(sk, flags & ~MSG_DONTWAIT,
				flags & MSG_DONTWAIT, &err);
	if (!skb)
		goto end;

	if (len > skb->len)
		len = skb->len;
	else if (len < skb->len)
		msg->msg_flags |= MSG_TRUNC;

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	err = skb_copy_datagram_msg(skb, 0, msg, len);
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	if (likely(err == 0))
		err = len;

	kfree_skb(skb);
end:
	return err;
}

static void pppol2tp_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
{
	struct pppol2tp_session *ps = l2tp_session_priv(session);
	struct sock *sk = NULL;

	/* If the socket is bound, send it in to PPP's input queue. Otherwise
	 * queue it on the session socket.
	 */
	sk = ps->sock;
	if (sk == NULL)
		goto no_sock;

	if (sk->sk_state & PPPOX_BOUND) {
		struct pppox_sock *po;
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		l2tp_dbg(session, L2TP_MSG_DATA,
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			 "%s: recv %d byte data frame, passing to ppp\n",
			 session->name, data_len);
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		po = pppox_sk(sk);
		ppp_input(&po->chan, skb);
	} else {
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		l2tp_dbg(session, L2TP_MSG_DATA,
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			 "%s: recv %d byte data frame, passing to L2TP socket\n",
			 session->name, data_len);
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		if (sock_queue_rcv_skb(sk, skb) < 0) {
			atomic_long_inc(&session->stats.rx_errors);
			kfree_skb(skb);
		}
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	}

	return;

no_sock:
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	l2tp_info(session, L2TP_MSG_DATA, "%s: no socket\n", session->name);
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	kfree_skb(skb);
}

static void pppol2tp_session_sock_hold(struct l2tp_session *session)
{
	struct pppol2tp_session *ps = l2tp_session_priv(session);

	if (ps->sock)
		sock_hold(ps->sock);
}

static void pppol2tp_session_sock_put(struct l2tp_session *session)
{
	struct pppol2tp_session *ps = l2tp_session_priv(session);

	if (ps->sock)
		sock_put(ps->sock);
}

/************************************************************************
 * Transmit handling
 ***********************************************************************/

/* This is the sendmsg for the PPPoL2TP pppol2tp_session socket.  We come here
 * when a user application does a sendmsg() on the session socket. L2TP and
 * PPP headers must be inserted into the user's data.
 */
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static int pppol2tp_sendmsg(struct socket *sock, struct msghdr *m,
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			    size_t total_len)
{
	struct sock *sk = sock->sk;
	struct sk_buff *skb;
	int error;
	struct l2tp_session *session;
	struct l2tp_tunnel *tunnel;
	struct pppol2tp_session *ps;
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	int uhlen;
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	error = -ENOTCONN;
	if (sock_flag(sk, SOCK_DEAD) || !(sk->sk_state & PPPOX_CONNECTED))
		goto error;

	/* Get session and tunnel contexts */
	error = -EBADF;
	session = pppol2tp_sock_to_session(sk);
	if (session == NULL)
		goto error;

	ps = l2tp_session_priv(session);
	tunnel = l2tp_sock_to_tunnel(ps->tunnel_sock);
	if (tunnel == NULL)
		goto error_put_sess;

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	uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;

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	/* Allocate a socket buffer */
	error = -ENOMEM;
	skb = sock_wmalloc(sk, NET_SKB_PAD + sizeof(struct iphdr) +
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			   uhlen + session->hdr_len +
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			   2 + total_len, /* 2 bytes for PPP_ALLSTATIONS & PPP_UI */
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			   0, GFP_KERNEL);
	if (!skb)
		goto error_put_sess_tun;

	/* Reserve space for headers. */
	skb_reserve(skb, NET_SKB_PAD);
	skb_reset_network_header(skb);
	skb_reserve(skb, sizeof(struct iphdr));
	skb_reset_transport_header(skb);
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	skb_reserve(skb, uhlen);
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	/* Add PPP header */
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	skb->data[0] = PPP_ALLSTATIONS;
	skb->data[1] = PPP_UI;
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	skb_put(skb, 2);

	/* Copy user data into skb */
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	error = memcpy_from_msg(skb_put(skb, total_len), m, total_len);
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	if (error < 0) {
		kfree_skb(skb);
		goto error_put_sess_tun;
	}

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	local_bh_disable();
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	l2tp_xmit_skb(session, skb, session->hdr_len);
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	local_bh_enable();
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	sock_put(ps->tunnel_sock);
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	sock_put(sk);
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	return total_len;
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error_put_sess_tun:
	sock_put(ps->tunnel_sock);
error_put_sess:
	sock_put(sk);
error:
	return error;
}

/* Transmit function called by generic PPP driver.  Sends PPP frame
 * over PPPoL2TP socket.
 *
 * This is almost the same as pppol2tp_sendmsg(), but rather than
 * being called with a msghdr from userspace, it is called with a skb
 * from the kernel.
 *
 * The supplied skb from ppp doesn't have enough headroom for the
 * insertion of L2TP, UDP and IP headers so we need to allocate more
 * headroom in the skb. This will create a cloned skb. But we must be
 * careful in the error case because the caller will expect to free
 * the skb it supplied, not our cloned skb. So we take care to always
 * leave the original skb unfreed if we return an error.
 */
static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
{
	struct sock *sk = (struct sock *) chan->private;
	struct sock *sk_tun;
	struct l2tp_session *session;
	struct l2tp_tunnel *tunnel;
	struct pppol2tp_session *ps;
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	int uhlen, headroom;
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	if (sock_flag(sk, SOCK_DEAD) || !(sk->sk_state & PPPOX_CONNECTED))
		goto abort;

	/* Get session and tunnel contexts from the socket */
	session = pppol2tp_sock_to_session(sk);
	if (session == NULL)
		goto abort;

	ps = l2tp_session_priv(session);
	sk_tun = ps->tunnel_sock;
	if (sk_tun == NULL)
		goto abort_put_sess;
	tunnel = l2tp_sock_to_tunnel(sk_tun);
	if (tunnel == NULL)
		goto abort_put_sess;

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	uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
	headroom = NET_SKB_PAD +
		   sizeof(struct iphdr) + /* IP header */
		   uhlen +		/* UDP header (if L2TP_ENCAPTYPE_UDP) */
		   session->hdr_len +	/* L2TP header */
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		   2;			/* 2 bytes for PPP_ALLSTATIONS & PPP_UI */
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	if (skb_cow_head(skb, headroom))
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		goto abort_put_sess_tun;

	/* Setup PPP header */
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	__skb_push(skb, 2);
	skb->data[0] = PPP_ALLSTATIONS;
	skb->data[1] = PPP_UI;
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	local_bh_disable();
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	l2tp_xmit_skb(session, skb, session->hdr_len);
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	local_bh_enable();
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	sock_put(sk_tun);
	sock_put(sk);
	return 1;

abort_put_sess_tun:
	sock_put(sk_tun);
abort_put_sess:
	sock_put(sk);
abort:
	/* Free the original skb */
	kfree_skb(skb);
	return 1;
}

/*****************************************************************************
 * Session (and tunnel control) socket create/destroy.
 *****************************************************************************/

/* Called by l2tp_core when a session socket is being closed.
 */
static void pppol2tp_session_close(struct l2tp_session *session)
{
	struct pppol2tp_session *ps = l2tp_session_priv(session);
	struct sock *sk = ps->sock;
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	struct socket *sock = sk->sk_socket;
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	BUG_ON(session->magic != L2TP_SESSION_MAGIC);

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	if (sock)
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		inet_shutdown(sock, SEND_SHUTDOWN);
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	/* Don't let the session go away before our socket does */
	l2tp_session_inc_refcount(session);
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}

/* Really kill the session socket. (Called from sock_put() if
 * refcnt == 0.)
 */
static void pppol2tp_session_destruct(struct sock *sk)
{
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	struct l2tp_session *session = sk->sk_user_data;
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	skb_queue_purge(&sk->sk_receive_queue);
	skb_queue_purge(&sk->sk_write_queue);

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	if (session) {
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		sk->sk_user_data = NULL;
		BUG_ON(session->magic != L2TP_SESSION_MAGIC);
		l2tp_session_dec_refcount(session);
	}
}

/* Called when the PPPoX socket (session) is closed.
 */
static int pppol2tp_release(struct socket *sock)
{
	struct sock *sk = sock->sk;
	struct l2tp_session *session;
	int error;

	if (!sk)
		return 0;

	error = -EBADF;
	lock_sock(sk);
	if (sock_flag(sk, SOCK_DEAD) != 0)
		goto error;

	pppox_unbind_sock(sk);

	/* Signal the death of the socket. */
	sk->sk_state = PPPOX_DEAD;
	sock_orphan(sk);
	sock->sk = NULL;

	session = pppol2tp_sock_to_session(sk);

	/* Purge any queued data */
	if (session != NULL) {
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		__l2tp_session_unhash(session);
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		l2tp_session_queue_purge(session);
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		sock_put(sk);
	}
	release_sock(sk);

	/* This will delete the session context via
	 * pppol2tp_session_destruct() if the socket's refcnt drops to
	 * zero.
	 */
	sock_put(sk);

	return 0;

error:
	release_sock(sk);
	return error;
}

static struct proto pppol2tp_sk_proto = {
	.name	  = "PPPOL2TP",
	.owner	  = THIS_MODULE,
	.obj_size = sizeof(struct pppox_sock),
};

static int pppol2tp_backlog_recv(struct sock *sk, struct sk_buff *skb)
{
	int rc;

	rc = l2tp_udp_encap_recv(sk, skb);
	if (rc)
		kfree_skb(skb);

	return NET_RX_SUCCESS;
}

/* socket() handler. Initialize a new struct sock.
 */
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static int pppol2tp_create(struct net *net, struct socket *sock, int kern)
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{
	int error = -ENOMEM;
	struct sock *sk;

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	sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pppol2tp_sk_proto, kern);
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	if (!sk)
		goto out;

	sock_init_data(sock, sk);

	sock->state  = SS_UNCONNECTED;
	sock->ops    = &pppol2tp_ops;

	sk->sk_backlog_rcv = pppol2tp_backlog_recv;
	sk->sk_protocol	   = PX_PROTO_OL2TP;
	sk->sk_family	   = PF_PPPOX;
	sk->sk_state	   = PPPOX_NONE;
	sk->sk_type	   = SOCK_STREAM;
	sk->sk_destruct	   = pppol2tp_session_destruct;

	error = 0;

out:
	return error;
}

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#if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
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static void pppol2tp_show(struct seq_file *m, void *arg)
{
	struct l2tp_session *session = arg;
	struct pppol2tp_session *ps = l2tp_session_priv(session);

	if (ps) {
		struct pppox_sock *po = pppox_sk(ps->sock);
		if (po)
			seq_printf(m, "   interface %s\n", ppp_dev_name(&po->chan));
	}
}
#endif

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/* connect() handler. Attach a PPPoX socket to a tunnel UDP socket
 */
static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
			    int sockaddr_len, int flags)
{
	struct sock *sk = sock->sk;
	struct sockaddr_pppol2tp *sp = (struct sockaddr_pppol2tp *) uservaddr;
	struct pppox_sock *po = pppox_sk(sk);
	struct l2tp_session *session = NULL;
	struct l2tp_tunnel *tunnel;
	struct pppol2tp_session *ps;
	struct dst_entry *dst;
	struct l2tp_session_cfg cfg = { 0, };
	int error = 0;
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	u32 tunnel_id, peer_tunnel_id;
	u32 session_id, peer_session_id;
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	bool drop_refcnt = false;
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	int ver = 2;
	int fd;
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	lock_sock(sk);

	error = -EINVAL;
	if (sp->sa_protocol != PX_PROTO_OL2TP)
		goto end;

	/* Check for already bound sockets */
	error = -EBUSY;
	if (sk->sk_state & PPPOX_CONNECTED)
		goto end;

	/* We don't supporting rebinding anyway */
	error = -EALREADY;
	if (sk->sk_user_data)
		goto end; /* socket is already attached */

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	/* Get params from socket address. Handle L2TPv2 and L2TPv3.
	 * This is nasty because there are different sockaddr_pppol2tp
	 * structs for L2TPv2, L2TPv3, over IPv4 and IPv6. We use
	 * the sockaddr size to determine which structure the caller
	 * is using.
	 */
	peer_tunnel_id = 0;
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	if (sockaddr_len == sizeof(struct sockaddr_pppol2tp)) {
		fd = sp->pppol2tp.fd;
		tunnel_id = sp->pppol2tp.s_tunnel;
		peer_tunnel_id = sp->pppol2tp.d_tunnel;
		session_id = sp->pppol2tp.s_session;
		peer_session_id = sp->pppol2tp.d_session;
	} else if (sockaddr_len == sizeof(struct sockaddr_pppol2tpv3)) {
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		struct sockaddr_pppol2tpv3 *sp3 =
			(struct sockaddr_pppol2tpv3 *) sp;
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		ver = 3;
		fd = sp3->pppol2tp.fd;
		tunnel_id = sp3->pppol2tp.s_tunnel;
		peer_tunnel_id = sp3->pppol2tp.d_tunnel;
		session_id = sp3->pppol2tp.s_session;
		peer_session_id = sp3->pppol2tp.d_session;
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	} else if (sockaddr_len == sizeof(struct sockaddr_pppol2tpin6)) {
		struct sockaddr_pppol2tpin6 *sp6 =
			(struct sockaddr_pppol2tpin6 *) sp;
		fd = sp6->pppol2tp.fd;
		tunnel_id = sp6->pppol2tp.s_tunnel;
		peer_tunnel_id = sp6->pppol2tp.d_tunnel;
		session_id = sp6->pppol2tp.s_session;
		peer_session_id = sp6->pppol2tp.d_session;
	} else if (sockaddr_len == sizeof(struct sockaddr_pppol2tpv3in6)) {
		struct sockaddr_pppol2tpv3in6 *sp6 =
			(struct sockaddr_pppol2tpv3in6 *) sp;
		ver = 3;
		fd = sp6->pppol2tp.fd;
		tunnel_id = sp6->pppol2tp.s_tunnel;
		peer_tunnel_id = sp6->pppol2tp.d_tunnel;
		session_id = sp6->pppol2tp.s_session;
		peer_session_id = sp6->pppol2tp.d_session;
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	} else {
		error = -EINVAL;
		goto end; /* bad socket address */
	}

	/* Don't bind if tunnel_id is 0 */
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	error = -EINVAL;
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	if (tunnel_id == 0)
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		goto end;

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	tunnel = l2tp_tunnel_find(sock_net(sk), tunnel_id);

657 658
	/* Special case: create tunnel context if session_id and
	 * peer_session_id is 0. Otherwise look up tunnel using supplied
659 660
	 * tunnel id.
	 */
661
	if ((session_id == 0) && (peer_session_id == 0)) {
662 663 664 665 666 667 668 669 670
		if (tunnel == NULL) {
			struct l2tp_tunnel_cfg tcfg = {
				.encap = L2TP_ENCAPTYPE_UDP,
				.debug = 0,
			};
			error = l2tp_tunnel_create(sock_net(sk), fd, ver, tunnel_id, peer_tunnel_id, &tcfg, &tunnel);
			if (error < 0)
				goto end;
		}
671 672 673 674 675 676 677 678 679 680 681 682 683 684
	} else {
		/* Error if we can't find the tunnel */
		error = -ENOENT;
		if (tunnel == NULL)
			goto end;

		/* Error if socket is not prepped */
		if (tunnel->sock == NULL)
			goto end;
	}

	if (tunnel->recv_payload_hook == NULL)
		tunnel->recv_payload_hook = pppol2tp_recv_payload_hook;

685 686
	if (tunnel->peer_tunnel_id == 0)
		tunnel->peer_tunnel_id = peer_tunnel_id;
687

688 689 690 691 692 693 694
	session = l2tp_session_get(sock_net(sk), tunnel, session_id, false);
	if (session) {
		drop_refcnt = true;
		ps = l2tp_session_priv(session);

		/* Using a pre-existing session is fine as long as it hasn't
		 * been connected yet.
695
		 */
696 697 698 699
		if (ps->sock) {
			error = -EEXIST;
			goto end;
		}
700

701 702 703
		/* consistency checks */
		if (ps->tunnel_sock != tunnel->sock) {
			error = -EEXIST;
704 705 706
			goto end;
		}
	} else {
707 708 709
		/* Default MTU must allow space for UDP/L2TP/PPP headers */
		cfg.mtu = 1500 - PPPOL2TP_HEADER_OVERHEAD;
		cfg.mru = cfg.mtu;
710

711 712 713 714 715
		session = l2tp_session_create(sizeof(struct pppol2tp_session),
					      tunnel, session_id,
					      peer_session_id, &cfg);
		if (IS_ERR(session)) {
			error = PTR_ERR(session);
716
			goto end;
717
		}
718 719
	}

720
	/* Associate session with its PPPoL2TP socket */
721 722 723 724 725 726 727
	ps = l2tp_session_priv(session);
	ps->owner	     = current->pid;
	ps->sock	     = sk;
	ps->tunnel_sock = tunnel->sock;

	session->recv_skb	= pppol2tp_recv;
	session->session_close	= pppol2tp_session_close;
728
#if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
729 730
	session->show		= pppol2tp_show;
#endif
731 732 733 734 735 736 737 738

	/* We need to know each time a skb is dropped from the reorder
	 * queue.
	 */
	session->ref = pppol2tp_session_sock_hold;
	session->deref = pppol2tp_session_sock_put;

	/* If PMTU discovery was enabled, use the MTU that was discovered */
739
	dst = sk_dst_get(tunnel->sock);
740
	if (dst != NULL) {
741 742
		u32 pmtu = dst_mtu(dst);

743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777
		if (pmtu != 0)
			session->mtu = session->mru = pmtu -
				PPPOL2TP_HEADER_OVERHEAD;
		dst_release(dst);
	}

	/* Special case: if source & dest session_id == 0x0000, this
	 * socket is being created to manage the tunnel. Just set up
	 * the internal context for use by ioctl() and sockopt()
	 * handlers.
	 */
	if ((session->session_id == 0) &&
	    (session->peer_session_id == 0)) {
		error = 0;
		goto out_no_ppp;
	}

	/* The only header we need to worry about is the L2TP
	 * header. This size is different depending on whether
	 * sequence numbers are enabled for the data channel.
	 */
	po->chan.hdrlen = PPPOL2TP_L2TP_HDR_SIZE_NOSEQ;

	po->chan.private = sk;
	po->chan.ops	 = &pppol2tp_chan_ops;
	po->chan.mtu	 = session->mtu;

	error = ppp_register_net_channel(sock_net(sk), &po->chan);
	if (error)
		goto end;

out_no_ppp:
	/* This is how we get the session context from the socket. */
	sk->sk_user_data = session;
	sk->sk_state = PPPOX_CONNECTED;
778
	l2tp_info(session, L2TP_MSG_CONTROL, "%s: created\n",
779
		  session->name);
780 781

end:
782 783
	if (drop_refcnt)
		l2tp_session_dec_refcount(session);
784 785 786 787 788
	release_sock(sk);

	return error;
}

789 790
#ifdef CONFIG_L2TP_V3

791 792 793 794
/* Called when creating sessions via the netlink interface. */
static int pppol2tp_session_create(struct net *net, struct l2tp_tunnel *tunnel,
				   u32 session_id, u32 peer_session_id,
				   struct l2tp_session_cfg *cfg)
795 796 797 798 799 800
{
	int error;
	struct l2tp_session *session;
	struct pppol2tp_session *ps;

	/* Error if tunnel socket is not prepped */
801 802
	if (!tunnel->sock) {
		error = -ENOENT;
803
		goto out;
804
	}
805 806 807 808 809 810 811 812 813 814 815

	/* Default MTU values. */
	if (cfg->mtu == 0)
		cfg->mtu = 1500 - PPPOL2TP_HEADER_OVERHEAD;
	if (cfg->mru == 0)
		cfg->mru = cfg->mtu;

	/* Allocate and initialize a new session context. */
	session = l2tp_session_create(sizeof(struct pppol2tp_session),
				      tunnel, session_id,
				      peer_session_id, cfg);
816 817
	if (IS_ERR(session)) {
		error = PTR_ERR(session);
818
		goto out;
819
	}
820 821 822 823

	ps = l2tp_session_priv(session);
	ps->tunnel_sock = tunnel->sock;

824
	l2tp_info(session, L2TP_MSG_CONTROL, "%s: created\n",
825
		  session->name);
826 827 828 829 830 831 832 833 834

	error = 0;

out:
	return error;
}

#endif /* CONFIG_L2TP_V3 */

835 836 837 838 839
/* getname() support.
 */
static int pppol2tp_getname(struct socket *sock, struct sockaddr *uaddr,
			    int *usockaddr_len, int peer)
{
840
	int len = 0;
841 842 843 844 845 846 847 848 849 850
	int error = 0;
	struct l2tp_session *session;
	struct l2tp_tunnel *tunnel;
	struct sock *sk = sock->sk;
	struct inet_sock *inet;
	struct pppol2tp_session *pls;

	error = -ENOTCONN;
	if (sk == NULL)
		goto end;
851
	if (!(sk->sk_state & PPPOX_CONNECTED))
852 853 854 855 856 857 858 859 860
		goto end;

	error = -EBADF;
	session = pppol2tp_sock_to_session(sk);
	if (session == NULL)
		goto end;

	pls = l2tp_session_priv(session);
	tunnel = l2tp_sock_to_tunnel(pls->tunnel_sock);
861
	if (tunnel == NULL)
862 863
		goto end_put_sess;

864
	inet = inet_sk(tunnel->sock);
865
	if ((tunnel->version == 2) && (tunnel->sock->sk_family == AF_INET)) {
866 867 868 869 870 871 872 873 874 875 876 877 878 879 880
		struct sockaddr_pppol2tp sp;
		len = sizeof(sp);
		memset(&sp, 0, len);
		sp.sa_family	= AF_PPPOX;
		sp.sa_protocol	= PX_PROTO_OL2TP;
		sp.pppol2tp.fd  = tunnel->fd;
		sp.pppol2tp.pid = pls->owner;
		sp.pppol2tp.s_tunnel = tunnel->tunnel_id;
		sp.pppol2tp.d_tunnel = tunnel->peer_tunnel_id;
		sp.pppol2tp.s_session = session->session_id;
		sp.pppol2tp.d_session = session->peer_session_id;
		sp.pppol2tp.addr.sin_family = AF_INET;
		sp.pppol2tp.addr.sin_port = inet->inet_dport;
		sp.pppol2tp.addr.sin_addr.s_addr = inet->inet_daddr;
		memcpy(uaddr, &sp, len);
881 882 883 884
#if IS_ENABLED(CONFIG_IPV6)
	} else if ((tunnel->version == 2) &&
		   (tunnel->sock->sk_family == AF_INET6)) {
		struct sockaddr_pppol2tpin6 sp;
885

886 887 888 889 890 891 892 893 894 895 896 897
		len = sizeof(sp);
		memset(&sp, 0, len);
		sp.sa_family	= AF_PPPOX;
		sp.sa_protocol	= PX_PROTO_OL2TP;
		sp.pppol2tp.fd  = tunnel->fd;
		sp.pppol2tp.pid = pls->owner;
		sp.pppol2tp.s_tunnel = tunnel->tunnel_id;
		sp.pppol2tp.d_tunnel = tunnel->peer_tunnel_id;
		sp.pppol2tp.s_session = session->session_id;
		sp.pppol2tp.d_session = session->peer_session_id;
		sp.pppol2tp.addr.sin6_family = AF_INET6;
		sp.pppol2tp.addr.sin6_port = inet->inet_dport;
898 899
		memcpy(&sp.pppol2tp.addr.sin6_addr, &tunnel->sock->sk_v6_daddr,
		       sizeof(tunnel->sock->sk_v6_daddr));
900 901 902 903
		memcpy(uaddr, &sp, len);
	} else if ((tunnel->version == 3) &&
		   (tunnel->sock->sk_family == AF_INET6)) {
		struct sockaddr_pppol2tpv3in6 sp;
904

905 906 907 908 909 910 911 912 913 914 915 916
		len = sizeof(sp);
		memset(&sp, 0, len);
		sp.sa_family	= AF_PPPOX;
		sp.sa_protocol	= PX_PROTO_OL2TP;
		sp.pppol2tp.fd  = tunnel->fd;
		sp.pppol2tp.pid = pls->owner;
		sp.pppol2tp.s_tunnel = tunnel->tunnel_id;
		sp.pppol2tp.d_tunnel = tunnel->peer_tunnel_id;
		sp.pppol2tp.s_session = session->session_id;
		sp.pppol2tp.d_session = session->peer_session_id;
		sp.pppol2tp.addr.sin6_family = AF_INET6;
		sp.pppol2tp.addr.sin6_port = inet->inet_dport;
917 918
		memcpy(&sp.pppol2tp.addr.sin6_addr, &tunnel->sock->sk_v6_daddr,
		       sizeof(tunnel->sock->sk_v6_daddr));
919 920
		memcpy(uaddr, &sp, len);
#endif
921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937
	} else if (tunnel->version == 3) {
		struct sockaddr_pppol2tpv3 sp;
		len = sizeof(sp);
		memset(&sp, 0, len);
		sp.sa_family	= AF_PPPOX;
		sp.sa_protocol	= PX_PROTO_OL2TP;
		sp.pppol2tp.fd  = tunnel->fd;
		sp.pppol2tp.pid = pls->owner;
		sp.pppol2tp.s_tunnel = tunnel->tunnel_id;
		sp.pppol2tp.d_tunnel = tunnel->peer_tunnel_id;
		sp.pppol2tp.s_session = session->session_id;
		sp.pppol2tp.d_session = session->peer_session_id;
		sp.pppol2tp.addr.sin_family = AF_INET;
		sp.pppol2tp.addr.sin_port = inet->inet_dport;
		sp.pppol2tp.addr.sin_addr.s_addr = inet->inet_daddr;
		memcpy(uaddr, &sp, len);
	}
938 939

	*usockaddr_len = len;
940
	error = 0;
941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962

	sock_put(pls->tunnel_sock);
end_put_sess:
	sock_put(sk);
end:
	return error;
}

/****************************************************************************
 * ioctl() handlers.
 *
 * The PPPoX socket is created for L2TP sessions: tunnels have their own UDP
 * sockets. However, in order to control kernel tunnel features, we allow
 * userspace to create a special "tunnel" PPPoX socket which is used for
 * control only.  Tunnel PPPoX sockets have session_id == 0 and simply allow
 * the user application to issue L2TP setsockopt(), getsockopt() and ioctl()
 * calls.
 ****************************************************************************/

static void pppol2tp_copy_stats(struct pppol2tp_ioc_stats *dest,
				struct l2tp_stats *stats)
{
963 964 965 966 967 968 969 970
	dest->tx_packets = atomic_long_read(&stats->tx_packets);
	dest->tx_bytes = atomic_long_read(&stats->tx_bytes);
	dest->tx_errors = atomic_long_read(&stats->tx_errors);
	dest->rx_packets = atomic_long_read(&stats->rx_packets);
	dest->rx_bytes = atomic_long_read(&stats->rx_bytes);
	dest->rx_seq_discards = atomic_long_read(&stats->rx_seq_discards);
	dest->rx_oos_packets = atomic_long_read(&stats->rx_oos_packets);
	dest->rx_errors = atomic_long_read(&stats->rx_errors);
971 972 973 974 975 976 977 978 979 980 981 982 983 984 985
}

/* Session ioctl helper.
 */
static int pppol2tp_session_ioctl(struct l2tp_session *session,
				  unsigned int cmd, unsigned long arg)
{
	struct ifreq ifr;
	int err = 0;
	struct sock *sk;
	int val = (int) arg;
	struct pppol2tp_session *ps = l2tp_session_priv(session);
	struct l2tp_tunnel *tunnel = session->tunnel;
	struct pppol2tp_ioc_stats stats;

986
	l2tp_dbg(session, L2TP_MSG_CONTROL,
987 988
		 "%s: pppol2tp_session_ioctl(cmd=%#x, arg=%#lx)\n",
		 session->name, cmd, arg);
989 990

	sk = ps->sock;
991 992 993
	if (!sk)
		return -EBADR;

994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008
	sock_hold(sk);

	switch (cmd) {
	case SIOCGIFMTU:
		err = -ENXIO;
		if (!(sk->sk_state & PPPOX_CONNECTED))
			break;

		err = -EFAULT;
		if (copy_from_user(&ifr, (void __user *) arg, sizeof(struct ifreq)))
			break;
		ifr.ifr_mtu = session->mtu;
		if (copy_to_user((void __user *) arg, &ifr, sizeof(struct ifreq)))
			break;

1009
		l2tp_info(session, L2TP_MSG_CONTROL, "%s: get mtu=%d\n",
1010
			  session->name, session->mtu);
1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024
		err = 0;
		break;

	case SIOCSIFMTU:
		err = -ENXIO;
		if (!(sk->sk_state & PPPOX_CONNECTED))
			break;

		err = -EFAULT;
		if (copy_from_user(&ifr, (void __user *) arg, sizeof(struct ifreq)))
			break;

		session->mtu = ifr.ifr_mtu;

1025
		l2tp_info(session, L2TP_MSG_CONTROL, "%s: set mtu=%d\n",
1026
			  session->name, session->mtu);
1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038
		err = 0;
		break;

	case PPPIOCGMRU:
		err = -ENXIO;
		if (!(sk->sk_state & PPPOX_CONNECTED))
			break;

		err = -EFAULT;
		if (put_user(session->mru, (int __user *) arg))
			break;

1039
		l2tp_info(session, L2TP_MSG_CONTROL, "%s: get mru=%d\n",
1040
			  session->name, session->mru);
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053
		err = 0;
		break;

	case PPPIOCSMRU:
		err = -ENXIO;
		if (!(sk->sk_state & PPPOX_CONNECTED))
			break;

		err = -EFAULT;
		if (get_user(val, (int __user *) arg))
			break;

		session->mru = val;
1054
		l2tp_info(session, L2TP_MSG_CONTROL, "%s: set mru=%d\n",
1055
			  session->name, session->mru);
1056 1057 1058 1059 1060 1061 1062 1063
		err = 0;
		break;

	case PPPIOCGFLAGS:
		err = -EFAULT;
		if (put_user(ps->flags, (int __user *) arg))
			break;

1064
		l2tp_info(session, L2TP_MSG_CONTROL, "%s: get flags=%d\n",
1065
			  session->name, ps->flags);
1066 1067 1068 1069 1070 1071 1072 1073
		err = 0;
		break;

	case PPPIOCSFLAGS:
		err = -EFAULT;
		if (get_user(val, (int __user *) arg))
			break;
		ps->flags = val;
1074
		l2tp_info(session, L2TP_MSG_CONTROL, "%s: set flags=%d\n",
1075
			  session->name, ps->flags);
1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090
		err = 0;
		break;

	case PPPIOCGL2TPSTATS:
		err = -ENXIO;
		if (!(sk->sk_state & PPPOX_CONNECTED))
			break;

		memset(&stats, 0, sizeof(stats));
		stats.tunnel_id = tunnel->tunnel_id;
		stats.session_id = session->session_id;
		pppol2tp_copy_stats(&stats, &session->stats);
		if (copy_to_user((void __user *) arg, &stats,
				 sizeof(stats)))
			break;
1091
		l2tp_info(session, L2TP_MSG_CONTROL, "%s: get L2TP stats\n",
1092
			  session->name);
1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118
		err = 0;
		break;

	default:
		err = -ENOSYS;
		break;
	}

	sock_put(sk);

	return err;
}

/* Tunnel ioctl helper.
 *
 * Note the special handling for PPPIOCGL2TPSTATS below. If the ioctl data
 * specifies a session_id, the session ioctl handler is called. This allows an
 * application to retrieve session stats via a tunnel socket.
 */
static int pppol2tp_tunnel_ioctl(struct l2tp_tunnel *tunnel,
				 unsigned int cmd, unsigned long arg)
{
	int err = 0;
	struct sock *sk;
	struct pppol2tp_ioc_stats stats;

1119
	l2tp_dbg(tunnel, L2TP_MSG_CONTROL,
1120 1121
		 "%s: pppol2tp_tunnel_ioctl(cmd=%#x, arg=%#lx)\n",
		 tunnel->name, cmd, arg);
1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139

	sk = tunnel->sock;
	sock_hold(sk);

	switch (cmd) {
	case PPPIOCGL2TPSTATS:
		err = -ENXIO;
		if (!(sk->sk_state & PPPOX_CONNECTED))
			break;

		if (copy_from_user(&stats, (void __user *) arg,
				   sizeof(stats))) {
			err = -EFAULT;
			break;
		}
		if (stats.session_id != 0) {
			/* resend to session ioctl handler */
			struct l2tp_session *session =
1140 1141 1142 1143 1144 1145 1146 1147 1148 1149
				l2tp_session_get(sock_net(sk), tunnel,
						 stats.session_id, true);

			if (session) {
				err = pppol2tp_session_ioctl(session, cmd,
							     arg);
				if (session->deref)
					session->deref(session);
				l2tp_session_dec_refcount(session);
			} else {
1150
				err = -EBADR;
1151
			}
1152 1153 1154 1155 1156 1157 1158 1159 1160 1161
			break;
		}
#ifdef CONFIG_XFRM
		stats.using_ipsec = (sk->sk_policy[0] || sk->sk_policy[1]) ? 1 : 0;
#endif
		pppol2tp_copy_stats(&stats, &tunnel->stats);
		if (copy_to_user((void __user *) arg, &stats, sizeof(stats))) {
			err = -EFAULT;
			break;
		}
1162
		l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: get L2TP stats\n",
1163
			  tunnel->name);
1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251
		err = 0;
		break;

	default:
		err = -ENOSYS;
		break;
	}

	sock_put(sk);

	return err;
}

/* Main ioctl() handler.
 * Dispatch to tunnel or session helpers depending on the socket.
 */
static int pppol2tp_ioctl(struct socket *sock, unsigned int cmd,
			  unsigned long arg)
{
	struct sock *sk = sock->sk;
	struct l2tp_session *session;
	struct l2tp_tunnel *tunnel;
	struct pppol2tp_session *ps;
	int err;

	if (!sk)
		return 0;

	err = -EBADF;
	if (sock_flag(sk, SOCK_DEAD) != 0)
		goto end;

	err = -ENOTCONN;
	if ((sk->sk_user_data == NULL) ||
	    (!(sk->sk_state & (PPPOX_CONNECTED | PPPOX_BOUND))))
		goto end;

	/* Get session context from the socket */
	err = -EBADF;
	session = pppol2tp_sock_to_session(sk);
	if (session == NULL)
		goto end;

	/* Special case: if session's session_id is zero, treat ioctl as a
	 * tunnel ioctl
	 */
	ps = l2tp_session_priv(session);
	if ((session->session_id == 0) &&
	    (session->peer_session_id == 0)) {
		err = -EBADF;
		tunnel = l2tp_sock_to_tunnel(ps->tunnel_sock);
		if (tunnel == NULL)
			goto end_put_sess;

		err = pppol2tp_tunnel_ioctl(tunnel, cmd, arg);
		sock_put(ps->tunnel_sock);
		goto end_put_sess;
	}

	err = pppol2tp_session_ioctl(session, cmd, arg);

end_put_sess:
	sock_put(sk);
end:
	return err;
}

/*****************************************************************************
 * setsockopt() / getsockopt() support.
 *
 * The PPPoX socket is created for L2TP sessions: tunnels have their own UDP
 * sockets. In order to control kernel tunnel features, we allow userspace to
 * create a special "tunnel" PPPoX socket which is used for control only.
 * Tunnel PPPoX sockets have session_id == 0 and simply allow the user
 * application to issue L2TP setsockopt(), getsockopt() and ioctl() calls.
 *****************************************************************************/

/* Tunnel setsockopt() helper.
 */
static int pppol2tp_tunnel_setsockopt(struct sock *sk,
				      struct l2tp_tunnel *tunnel,
				      int optname, int val)
{
	int err = 0;

	switch (optname) {
	case PPPOL2TP_SO_DEBUG:
		tunnel->debug = val;
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		l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: set debug=%x\n",
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			  tunnel->name, tunnel->debug);
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		break;

	default:
		err = -ENOPROTOOPT;
		break;
	}

	return err;
}

/* Session setsockopt helper.
 */
static int pppol2tp_session_setsockopt(struct sock *sk,
				       struct l2tp_session *session,
				       int optname, int val)
{
	int err = 0;
	struct pppol2tp_session *ps = l2tp_session_priv(session);

	switch (optname) {
	case PPPOL2TP_SO_RECVSEQ:
		if ((val != 0) && (val != 1)) {
			err = -EINVAL;
			break;
		}
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		session->recv_seq = !!val;
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		l2tp_info(session, L2TP_MSG_CONTROL,
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			  "%s: set recv_seq=%d\n",
			  session->name, session->recv_seq);
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		break;

	case PPPOL2TP_SO_SENDSEQ:
		if ((val != 0) && (val != 1)) {
			err = -EINVAL;
			break;
		}
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		session->send_seq = !!val;
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		{
			struct sock *ssk      = ps->sock;
			struct pppox_sock *po = pppox_sk(ssk);
			po->chan.hdrlen = val ? PPPOL2TP_L2TP_HDR_SIZE_SEQ :
				PPPOL2TP_L2TP_HDR_SIZE_NOSEQ;
		}
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		l2tp_session_set_header_len(session, session->tunnel->version);
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		l2tp_info(session, L2TP_MSG_CONTROL,
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			  "%s: set send_seq=%d\n",
			  session->name, session->send_seq);
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		break;

	case PPPOL2TP_SO_LNSMODE:
		if ((val != 0) && (val != 1)) {
			err = -EINVAL;
			break;
		}
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		session->lns_mode = !!val;
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		l2tp_info(session, L2TP_MSG_CONTROL,
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			  "%s: set lns_mode=%d\n",
			  session->name, session->lns_mode);
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		break;

	case PPPOL2TP_SO_DEBUG:
		session->debug = val;
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		l2tp_info(session, L2TP_MSG_CONTROL, "%s: set debug=%x\n",
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			  session->name, session->debug);
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		break;

	case PPPOL2TP_SO_REORDERTO:
		session->reorder_timeout = msecs_to_jiffies(val);
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		l2tp_info(session, L2TP_MSG_CONTROL,
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			  "%s: set reorder_timeout=%d\n",
			  session->name, session->reorder_timeout);
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		break;

	default:
		err = -ENOPROTOOPT;
		break;
	}

	return err;
}

/* Main setsockopt() entry point.
 * Does API checks, then calls either the tunnel or session setsockopt
 * handler, according to whether the PPPoL2TP socket is a for a regular
 * session or the special tunnel type.
 */
static int pppol2tp_setsockopt(struct socket *sock, int level, int optname,
			       char __user *optval, unsigned int optlen)
{
	struct sock *sk = sock->sk;
	struct l2tp_session *session;
	struct l2tp_tunnel *tunnel;
	struct pppol2tp_session *ps;
	int val;
	int err;

	if (level != SOL_PPPOL2TP)
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		return -EINVAL;
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	if (optlen < sizeof(int))
		return -EINVAL;

	if (get_user(val, (int __user *)optval))
		return -EFAULT;

	err = -ENOTCONN;
	if (sk->sk_user_data == NULL)
		goto end;

	/* Get session context from the socket */
	err = -EBADF;
	session = pppol2tp_sock_to_session(sk);
	if (session == NULL)
		goto end;

	/* Special case: if session_id == 0x0000, treat as operation on tunnel
	 */
	ps = l2tp_session_priv(session);
	if ((session->session_id == 0) &&
	    (session->peer_session_id == 0)) {
		err = -EBADF;
		tunnel = l2tp_sock_to_tunnel(ps->tunnel_sock);
		if (tunnel == NULL)
			goto end_put_sess;

		err = pppol2tp_tunnel_setsockopt(sk, tunnel, optname, val);
		sock_put(ps->tunnel_sock);
	} else
		err = pppol2tp_session_setsockopt(sk, session, optname, val);

end_put_sess:
	sock_put(sk);
end:
	return err;
}

/* Tunnel getsockopt helper. Called with sock locked.
 */
static int pppol2tp_tunnel_getsockopt(struct sock *sk,
				      struct l2tp_tunnel *tunnel,
				      int optname, int *val)
{
	int err = 0;

	switch (optname) {
	case PPPOL2TP_SO_DEBUG:
		*val = tunnel->debug;
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		l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: get debug=%x\n",
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			  tunnel->name, tunnel->debug);
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		break;

	default:
		err = -ENOPROTOOPT;
		break;
	}

	return err;
}

/* Session getsockopt helper. Called with sock locked.
 */
static int pppol2tp_session_getsockopt(struct sock *sk,
				       struct l2tp_session *session,
				       int optname, int *val)
{
	int err = 0;

	switch (optname) {
	case PPPOL2TP_SO_RECVSEQ:
		*val = session->recv_seq;
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		l2tp_info(session, L2TP_MSG_CONTROL,
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			  "%s: get recv_seq=%d\n", session->name, *val);
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		break;

	case PPPOL2TP_SO_SENDSEQ:
		*val = session->send_seq;
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		l2tp_info(session, L2TP_MSG_CONTROL,
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			  "%s: get send_seq=%d\n", session->name, *val);
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		break;

	case PPPOL2TP_SO_LNSMODE:
		*val = session->lns_mode;
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		l2tp_info(session, L2TP_MSG_CONTROL,
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			  "%s: get lns_mode=%d\n", session->name, *val);
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		break;

	case PPPOL2TP_SO_DEBUG:
		*val = session->debug;
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		l2tp_info(session, L2TP_MSG_CONTROL, "%s: get debug=%d\n",
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			  session->name, *val);
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		break;

	case PPPOL2TP_SO_REORDERTO:
		*val = (int) jiffies_to_msecs(session->reorder_timeout);
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		l2tp_info(session, L2TP_MSG_CONTROL,
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			  "%s: get reorder_timeout=%d\n", session->name, *val);
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		break;

	default:
		err = -ENOPROTOOPT;
	}

	return err;
}

/* Main getsockopt() entry point.
 * Does API checks, then calls either the tunnel or session getsockopt
 * handler, according to whether the PPPoX socket is a for a regular session
 * or the special tunnel type.
 */
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static int pppol2tp_getsockopt(struct socket *sock, int level, int optname,
			       char __user *optval, int __user *optlen)
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{
	struct sock *sk = sock->sk;
	struct l2tp_session *session;
	struct l2tp_tunnel *tunnel;
	int val, len;
	int err;
	struct pppol2tp_session *ps;

	if (level != SOL_PPPOL2TP)
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		return -EINVAL;
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	if (get_user(len, optlen))
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		return -EFAULT;

	len = min_t(unsigned int, len, sizeof(int));

	if (len < 0)
		return -EINVAL;

	err = -ENOTCONN;
	if (sk->sk_user_data == NULL)
		goto end;

	/* Get the session context */
	err = -EBADF;
	session = pppol2tp_sock_to_session(sk);
	if (session == NULL)
		goto end;

	/* Special case: if session_id == 0x0000, treat as operation on tunnel */
	ps = l2tp_session_priv(session);
	if ((session->session_id == 0) &&
	    (session->peer_session_id == 0)) {
		err = -EBADF;
		tunnel = l2tp_sock_to_tunnel(ps->tunnel_sock);
		if (tunnel == NULL)
			goto end_put_sess;

		err = pppol2tp_tunnel_getsockopt(sk, tunnel, optname, &val);
		sock_put(ps->tunnel_sock);
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		if (err)
			goto end_put_sess;
	} else {
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		err = pppol2tp_session_getsockopt(sk, session, optname, &val);
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		if (err)
			goto end_put_sess;
	}
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	err = -EFAULT;
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	if (put_user(len, optlen))
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		goto end_put_sess;

	if (copy_to_user((void __user *) optval, &val, len))
		goto end_put_sess;

	err = 0;

end_put_sess:
	sock_put(sk);
end:
	return err;
}

/*****************************************************************************
 * /proc filesystem for debug
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 * Since the original pppol2tp driver provided /proc/net/pppol2tp for
 * L2TPv2, we dump only L2TPv2 tunnels and sessions here.
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 *****************************************************************************/

static unsigned int pppol2tp_net_id;

#ifdef CONFIG_PROC_FS

struct pppol2tp_seq_data {
	struct seq_net_private p;
	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 pppol2tp_next_tunnel(struct net *net, struct pppol2tp_seq_data *pd)
{
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	for (;;) {
		pd->tunnel = l2tp_tunnel_find_nth(net, pd->tunnel_idx);
		pd->tunnel_idx++;

		if (pd->tunnel == NULL)
			break;

		/* Ignore L2TPv3 tunnels */
		if (pd->tunnel->version < 3)
			break;
	}
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}

static void pppol2tp_next_session(struct net *net, struct pppol2tp_seq_data *pd)
{
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	pd->session = l2tp_session_get_nth(pd->tunnel, pd->session_idx, true);
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	pd->session_idx++;
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	if (pd->session == NULL) {
		pd->session_idx = 0;
		pppol2tp_next_tunnel(net, pd);
	}
}

static void *pppol2tp_seq_start(struct seq_file *m, loff_t *offs)
{
	struct pppol2tp_seq_data *pd = SEQ_START_TOKEN;
	loff_t pos = *offs;
	struct net *net;

	if (!pos)
		goto out;

	BUG_ON(m->private == NULL);
	pd = m->private;
	net = seq_file_net(m);

	if (pd->tunnel == NULL)
		pppol2tp_next_tunnel(net, pd);
	else
		pppol2tp_next_session(net, pd);

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

out:
	return pd;
}

static void *pppol2tp_seq_next(struct seq_file *m, void *v, loff_t *pos)
{
	(*pos)++;
	return NULL;
}

static void pppol2tp_seq_stop(struct seq_file *p, void *v)
{
	/* nothing to do */
}

static void pppol2tp_seq_tunnel_show(struct seq_file *m, void *v)
{
	struct l2tp_tunnel *tunnel = v;

	seq_printf(m, "\nTUNNEL '%s', %c %d\n",
		   tunnel->name,
		   (tunnel == tunnel->sock->sk_user_data) ? 'Y' : 'N',
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		   refcount_read(&tunnel->ref_count) - 1);
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	seq_printf(m, " %08x %ld/%ld/%ld %ld/%ld/%ld\n",
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		   tunnel->debug,
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		   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));
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}

static void pppol2tp_seq_session_show(struct seq_file *m, void *v)
{
	struct l2tp_session *session = v;
	struct l2tp_tunnel *tunnel = session->tunnel;
	struct pppol2tp_session *ps = l2tp_session_priv(session);
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	struct pppox_sock *po = pppox_sk(ps->sock);
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	u32 ip = 0;
	u16 port = 0;

	if (tunnel->sock) {
		struct inet_sock *inet = inet_sk(tunnel->sock);
		ip = ntohl(inet->inet_saddr);
		port = ntohs(inet->inet_sport);
	}

	seq_printf(m, "  SESSION '%s' %08X/%d %04X/%04X -> "
		   "%04X/%04X %d %c\n",
		   session->name, ip, port,
		   tunnel->tunnel_id,
		   session->session_id,
		   tunnel->peer_tunnel_id,
		   session->peer_session_id,
		   ps->sock->sk_state,
		   (session == ps->sock->sk_user_data) ?
		   'Y' : 'N');
	seq_printf(m, "   %d/%d/%c/%c/%s %08x %u\n",
		   session->mtu, session->mru,
		   session->recv_seq ? 'R' : '-',
		   session->send_seq ? 'S' : '-',
		   session->lns_mode ? "LNS" : "LAC",
		   session->debug,
		   jiffies_to_msecs(session->reorder_timeout));
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	seq_printf(m, "   %hu/%hu %ld/%ld/%ld %ld/%ld/%ld\n",
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		   session->nr, session->ns,
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		   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));
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	if (po)
		seq_printf(m, "   interface %s\n", ppp_dev_name(&po->chan));
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}

static int pppol2tp_seq_show(struct seq_file *m, void *v)
{
	struct pppol2tp_seq_data *pd = v;

	/* display header on line 1 */
	if (v == SEQ_START_TOKEN) {
		seq_puts(m, "PPPoL2TP driver info, " PPPOL2TP_DRV_VERSION "\n");
		seq_puts(m, "TUNNEL name, user-data-ok session-count\n");
		seq_puts(m, " debug tx-pkts/bytes/errs rx-pkts/bytes/errs\n");
		seq_puts(m, "  SESSION name, addr/port src-tid/sid "
			 "dest-tid/sid state user-data-ok\n");
		seq_puts(m, "   mtu/mru/rcvseq/sendseq/lns debug reorderto\n");
		seq_puts(m, "   nr/ns tx-pkts/bytes/errs rx-pkts/bytes/errs\n");
		goto out;
	}

	/* Show the tunnel or session context.
	 */
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	if (!pd->session) {
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		pppol2tp_seq_tunnel_show(m, pd->tunnel);
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	} else {
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		pppol2tp_seq_session_show(m, pd->session);
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		if (pd->session->deref)
			pd->session->deref(pd->session);
		l2tp_session_dec_refcount(pd->session);
	}
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out:
	return 0;
}

static const struct seq_operations pppol2tp_seq_ops = {
	.start		= pppol2tp_seq_start,
	.next		= pppol2tp_seq_next,
	.stop		= pppol2tp_seq_stop,
	.show		= pppol2tp_seq_show,
};

/* Called when our /proc file is opened. We allocate data for use when
 * iterating our tunnel / session contexts and store it in the private
 * data of the seq_file.
 */
static int pppol2tp_proc_open(struct inode *inode, struct file *file)
{
	return seq_open_net(inode, file, &pppol2tp_seq_ops,
			    sizeof(struct pppol2tp_seq_data));
}

static const struct file_operations pppol2tp_proc_fops = {
	.owner		= THIS_MODULE,
	.open		= pppol2tp_proc_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= seq_release_net,
};

#endif /* CONFIG_PROC_FS */

/*****************************************************************************
 * Network namespace
 *****************************************************************************/

static __net_init int pppol2tp_init_net(struct net *net)
{
	struct proc_dir_entry *pde;
	int err = 0;

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	pde = proc_create("pppol2tp", S_IRUGO, net->proc_net,
			  &pppol2tp_proc_fops);
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	if (!pde) {
		err = -ENOMEM;
		goto out;
	}

out:
	return err;
}

static __net_exit void pppol2tp_exit_net(struct net *net)
{
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	remove_proc_entry("pppol2tp", net->proc_net);
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}

static struct pernet_operations pppol2tp_net_ops = {
	.init = pppol2tp_init_net,
	.exit = pppol2tp_exit_net,
	.id   = &pppol2tp_net_id,
};

/*****************************************************************************
 * Init and cleanup
 *****************************************************************************/

static const struct proto_ops pppol2tp_ops = {
	.family		= AF_PPPOX,
	.owner		= THIS_MODULE,
	.release	= pppol2tp_release,
	.bind		= sock_no_bind,
	.connect	= pppol2tp_connect,
	.socketpair	= sock_no_socketpair,
	.accept		= sock_no_accept,
	.getname	= pppol2tp_getname,
	.poll		= datagram_poll,
	.listen		= sock_no_listen,
	.shutdown	= sock_no_shutdown,
	.setsockopt	= pppol2tp_setsockopt,
	.getsockopt	= pppol2tp_getsockopt,
	.sendmsg	= pppol2tp_sendmsg,
	.recvmsg	= pppol2tp_recvmsg,
	.mmap		= sock_no_mmap,
	.ioctl		= pppox_ioctl,
};

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static const struct pppox_proto pppol2tp_proto = {
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	.create		= pppol2tp_create,
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	.ioctl		= pppol2tp_ioctl,
	.owner		= THIS_MODULE,
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};

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#ifdef CONFIG_L2TP_V3

static const struct l2tp_nl_cmd_ops pppol2tp_nl_cmd_ops = {
	.session_create	= pppol2tp_session_create,
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	.session_delete	= l2tp_session_delete,
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};

#endif /* CONFIG_L2TP_V3 */

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static int __init pppol2tp_init(void)
{
	int err;

	err = register_pernet_device(&pppol2tp_net_ops);
	if (err)
		goto out;

	err = proto_register(&pppol2tp_sk_proto, 0);
	if (err)
		goto out_unregister_pppol2tp_pernet;

	err = register_pppox_proto(PX_PROTO_OL2TP, &pppol2tp_proto);
	if (err)
		goto out_unregister_pppol2tp_proto;

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#ifdef CONFIG_L2TP_V3
	err = l2tp_nl_register_ops(L2TP_PWTYPE_PPP, &pppol2tp_nl_cmd_ops);
	if (err)
		goto out_unregister_pppox;
#endif