// SPDX-License-Identifier: GPL-2.0-only
/* L2TP core.
*
* Copyright (c) 2008,2009,2010 Katalix Systems Ltd
*
* This file contains some code of the original L2TPv2 pppol2tp
* driver, which has the following copyright:
*
* Authors: Martijn van Oosterhout <kleptog@svana.org>
* James Chapman (jchapman@katalix.com)
* Contributors:
* Michal Ostrowski <mostrows@speakeasy.net>
* Arnaldo Carvalho de Melo <acme@xconectiva.com.br>
* David S. Miller (davem@redhat.com)
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/string.h>
#include <linux/list.h>
#include <linux/rculist.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/in.h>
#include <linux/ip.h>
#include <linux/udp.h>
#include <linux/l2tp.h>
#include <linux/sort.h>
#include <linux/file.h>
#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/udp_tunnel.h>
#include <net/inet_common.h>
#include <net/xfrm.h>
#include <net/protocol.h>
#include <net/inet6_connection_sock.h>
#include <net/inet_ecn.h>
#include <net/ip6_route.h>
#include <net/ip6_checksum.h>
#include <asm/byteorder.h>
#include <linux/atomic.h>
#include "l2tp_core.h"
#define CREATE_TRACE_POINTS
#include "trace.h"
#define L2TP_DRV_VERSION "V2.0"
/* L2TP header constants */
#define L2TP_HDRFLAG_T 0x8000
#define L2TP_HDRFLAG_L 0x4000
#define L2TP_HDRFLAG_S 0x0800
#define L2TP_HDRFLAG_O 0x0200
#define L2TP_HDRFLAG_P 0x0100
#define L2TP_HDR_VER_MASK 0x000F
#define L2TP_HDR_VER_2 0x0002
#define L2TP_HDR_VER_3 0x0003
/* L2TPv3 default L2-specific sublayer */
#define L2TP_SLFLAG_S 0x40000000
#define L2TP_SL_SEQ_MASK 0x00ffffff
#define L2TP_HDR_SIZE_MAX 14
/* Default trace flags */
#define L2TP_DEFAULT_DEBUG_FLAGS 0
#define L2TP_DEPTH_NESTING 2
#if L2TP_DEPTH_NESTING == SINGLE_DEPTH_NESTING
#error "L2TP requires its own lockdep subclass"
#endif
/* Private data stored for received packets in the skb.
*/
struct l2tp_skb_cb {
u32 ns;
u16 has_seq;
u16 length;
unsigned long expires;
};
#define L2TP_SKB_CB(skb) ((struct l2tp_skb_cb *)&(skb)->cb[sizeof(struct inet_skb_parm)])
static struct workqueue_struct *l2tp_wq;
/* per-net private data for this module */
static unsigned int l2tp_net_id;
struct l2tp_net {
/* Lock for write access to l2tp_tunnel_idr */
spinlock_t l2tp_tunnel_idr_lock;
struct idr l2tp_tunnel_idr;
/* Lock for write access to l2tp_v[23]_session_idr/htable */
spinlock_t l2tp_session_idr_lock;
struct idr l2tp_v2_session_idr;
struct idr l2tp_v3_session_idr;
struct hlist_head l2tp_v3_session_htable[16];
};
static u32 l2tp_v2_session_key(u16 tunnel_id, u16 session_id)
{
return ((u32)tunnel_id) << 16 | session_id;
}
static unsigned long l2tp_v3_session_hashkey(struct sock *sk, u32 session_id)
{
return ((unsigned long)sk) + session_id;
}
#if IS_ENABLED(CONFIG_IPV6)
static bool l2tp_sk_is_v6(struct sock *sk)
{
return sk->sk_family == PF_INET6 &&
!ipv6_addr_v4mapped(&sk->sk_v6_daddr);
}
#endif
static struct l2tp_net *l2tp_pernet(const struct net *net)
{
return net_generic(net, l2tp_net_id);
}
static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
{
struct sock *sk = tunnel->sock;
trace_free_tunnel(tunnel);
if (sk) {
/* Disable udp encapsulation */
switch (tunnel->encap) {
case L2TP_ENCAPTYPE_UDP:
/* No longer an encapsulation socket. See net/ipv4/udp.c */
WRITE_ONCE(udp_sk(sk)->encap_type, 0);
udp_sk(sk)->encap_rcv = NULL;
udp_sk(sk)->encap_destroy = NULL;
break;
case L2TP_ENCAPTYPE_IP:
break;
}
tunnel->sock = NULL;
sock_put(sk);
}
kfree_rcu(tunnel, rcu);
}
static void l2tp_session_free(struct l2tp_session *session)
{
trace_free_session(session);
if (session->tunnel)
l2tp_tunnel_put(session->tunnel);
kfree_rcu(session, rcu);
}
struct l2tp_tunnel *l2tp_sk_to_tunnel(const struct sock *sk)
{
const struct net *net = sock_net(sk);
unsigned long tunnel_id, tmp;
struct l2tp_tunnel *tunnel;
struct l2tp_net *pn;
rcu_read_lock_bh();
pn = l2tp_pernet(net);
idr_for_each_entry_ul(&pn->l2tp_tunnel_idr, tunnel, tmp, tunnel_id) {
if (tunnel &&
tunnel->sock == sk &&
refcount_inc_not_zero(&tunnel->ref_count)) {
rcu_read_unlock_bh();
return tunnel;
}
}
rcu_read_unlock_bh();
return NULL;
}
EXPORT_SYMBOL_GPL(l2tp_sk_to_tunnel);
void l2tp_tunnel_put(struct l2tp_tunnel *tunnel)
{
if (refcount_dec_and_test(&tunnel->ref_count))
l2tp_tunnel_free(tunnel);
}
EXPORT_SYMBOL_GPL(l2tp_tunnel_put);
void l2tp_session_put(struct l2tp_session *session)
{
if (refcount_dec_and_test(&session->ref_count))
l2tp_session_free(session);
}
EXPORT_SYMBOL_GPL(l2tp_session_put);
/* Lookup a tunnel. A new reference is held on the returned tunnel. */
struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id)
{
const struct l2tp_net *pn = l2tp_pernet(net);
struct l2tp_tunnel *tunnel;
rcu_read_lock_bh();
tunnel = idr_find(&pn->l2tp_tunnel_idr, tunnel_id);
if (tunnel && refcount_inc_not_zero(&tunnel->ref_count)) {
rcu_read_unlock_bh();
return tunnel;
}
rcu_read_unlock_bh();
return NULL;
}
EXPORT_SYMBOL_GPL(l2tp_tunnel_get);
struct l2tp_tunnel *l2tp_tunnel_get_next(const struct net *net, unsigned long *key)
{
struct l2tp_net *pn = l2tp_pernet(net);
struct l2tp_tunnel *tunnel = NULL;
rcu_read_lock_bh();
again:
tunnel = idr_get_next_ul(&pn->l2tp_tunnel_idr, key);
if (tunnel) {
if (refcount_inc_not_zero(&tunnel->ref_count)) {
rcu_read_unlock_bh();
return tunnel;
}
(*key)++;
goto again;
}
rcu_read_unlock_bh();
return NULL;
}
EXPORT_SYMBOL_GPL(l2tp_tunnel_get_next);
struct l2tp_session *l2tp_v3_session_get(const struct net *net, struct sock *sk, u32 session_id)
{
const struct l2tp_net *pn = l2tp_pernet(net);
struct l2tp_session *session;
rcu_read_lock_bh();
session = idr_find(&pn->l2tp_v3_session_idr, session_id);
if (session && !hash_hashed(&session->hlist) &&
refcount_inc_not_zero(&session->ref_count)) {
rcu_read_unlock_bh();
return session;
}
/* If we get here and session is non-NULL, the session_id
* collides with one in another tunnel. If sk is non-NULL,
* find the session matching sk.
*/
if (session && sk) {
unsigned long key = l2tp_v3_session_hashkey(sk, session->session_id);
hash_for_each_possible_rcu(pn->l2tp_v3_session_htable, session,
hlist, key) {
/* session->tunnel may be NULL if another thread is in
* l2tp_session_register and has added an item to
* l2tp_v3_session_htable but hasn't yet added the
* session to its tunnel's session_list.
*/
struct l2tp_tunnel *tunnel = READ_ONCE(session->tunnel);
if (session->session_id == session_id &&
tunnel && tunnel->sock == sk &&
refcount_inc_not_zero(&session->ref_count)) {
rcu_read_unlock_bh();
return session;
}
}
}
rcu_read_unlock_bh();
return NULL;
}
EXPORT_SYMBOL_GPL(l2tp_v3_session_get);
struct l2tp_session *l2tp_v2_session_get(const struct net *net, u16 tunnel_id, u16 session_id)
{
u32 session_key = l2tp_v2_session_key(tunnel_id, session_id);
const struct l2tp_net *pn = l2tp_pernet(net);
struct l2tp_session *session;
rcu_read_lock_bh();
session = idr_find(&pn->l2tp_v2_session_idr, session_key);
if (session && refcount_inc_not_zero(&session->ref_count)) {
rcu_read_unlock_bh();
return session;
}
rcu_read_unlock_bh();
return NULL;
}
EXPORT_SYMBOL_GPL(l2tp_v2_session_get);
struct l2tp_session *l2tp_session_get(const struct net *net, struct sock *sk, int pver,
u32 tunnel_id, u32 session_id)
{
if (pver == L2TP_HDR_VER_2)
return l2tp_v2_session_get(net, tunnel_id, session_id);
else
return l2tp_v3_session_get(net, sk, session_id);
}
EXPORT_SYMBOL_GPL(l2tp_session_get);
static struct l2tp_session *l2tp_v2_session_get_next(const struct net *net,
u16 tid,
unsigned long *key)
{
struct l2tp_net *pn = l2tp_pernet(net);
struct l2tp_session *session = NULL;
/* Start searching within the range of the tid */
if (*key == 0)
*key = l2tp_v2_session_key(tid, 0);
rcu_read_lock_bh();
again:
session = idr_get_next_ul(&pn->l2tp_v2_session_idr, key);
if (session) {
struct l2tp_tunnel *tunnel = READ_ONCE(session->tunnel);
/* ignore sessions with id 0 as they are internal for pppol2tp */
if (session->session_id == 0) {
(*key)++;
goto again;
}
if (tunnel->tunnel_id == tid &&
refcount_inc_not_zero(&session->ref_count)) {
rcu_read_unlock_bh();
return session;
}
(*key)++;
if (tunnel->tunnel_id == tid)
goto again;
}
rcu_read_unlock_bh();
return NULL;
}
static struct l2tp_session *l2tp_v3_session_get_next(const struct net *net,
u32 tid, struct sock *sk,
unsigned long *key)
{
struct l2tp_net *pn = l2tp_pernet(net);
struct l2tp_session *session = NULL;
rcu_read_lock_bh();
again:
session = idr_get_next_ul(&pn->l2tp_v3_session_idr, key);
if (session && !hash_hashed(&session->hlist)) {
struct l2tp_tunnel *tunnel = READ_ONCE(session->tunnel);
if (tunnel && tunnel->tunnel_id == tid &&
refcount_inc_not_zero(&session->ref_count)) {
rcu_read_unlock_bh();
return session;
}
(*key)++;
goto again;
}
/* If we get here and session is non-NULL, the IDR entry may be one
* where the session_id collides with one in another tunnel. Check
* session_htable for a match. There can only be one session of a given
* ID per tunnel so we can return as soon as a match is found.
*/
if (session && hash_hashed(&session->hlist)) {
unsigned long hkey = l2tp_v3_session_hashkey(sk, session->session_id);
u32 sid = session->session_id;
hash_for_each_possible_rcu(pn->l2tp_v3_session_htable, session,
hlist, hkey) {
struct l2tp_tunnel *tunnel = READ_ONCE(session->tunnel);
if (session->session_id == sid &&
tunnel && tunnel->tunnel_id == tid &&
refcount_inc_not_zero(&session->ref_count)) {
rcu_read_unlock_bh();
return session;
}
}
/* If no match found, the colliding session ID isn't in our
* tunnel so try the next session ID.
*/
(*key)++;
goto again;
}
rcu_read_unlock_bh();
return NULL;
}
struct l2tp_session *l2tp_session_get_next(const struct net *net, struct sock *sk, int pver,
u32 tunnel_id, unsigned long *key)
{
if (pver == L2TP_HDR_VER_2)
return l2tp_v2_session_get_next(net, tunnel_id, key);
else
return l2tp_v3_session_get_next(net, tunnel_id, sk, key);
}
EXPORT_SYMBOL_GPL(l2tp_session_get_next);
/* Lookup a session by interface name.
* This is very inefficient but is only used by management interfaces.
*/
struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
const char *ifname)
{
struct l2tp_net *pn = l2tp_pernet(net);
unsigned long tunnel_id, tmp;
struct l2tp_session *session;
struct l2tp_tunnel *tunnel;
rcu_read_lock_bh();
idr_for_each_entry_ul(&pn->l2tp_tunnel_idr, tunnel, tmp, tunnel_id) {
if (tunnel) {
list_for_each_entry_rcu(session, &tunnel->session_list, list) {
if (strcmp(session->ifname, ifname))
continue;
if (!refcount_inc_not_zero(&session->ref_count))
continue;
rcu_read_unlock_bh();
return session;
}
}
}
rcu_read_unlock_bh();
return NULL;
}
EXPORT_SYMBOL_GPL(l2tp_session_get_by_ifname);
static void l2tp_session_coll_list_add(struct l2tp_session_coll_list *clist,
struct l2tp_session *session)
{
refcount_inc(&session->ref_count);
WARN_ON_ONCE(session->coll_list);
session->coll_list = clist;
spin_lock(&clist->lock);
list_add(&session->clist, &clist->list);
spin_unlock(&clist->lock);
}
static int l2tp_session_collision_add(struct l2tp_net *pn,
struct l2tp_session *session1,
struct l2tp_session *session2)
{
struct l2tp_session_coll_list *clist;
lockdep_assert_held(&pn->l2tp_session_idr_lock);
if (!session2)
return -EEXIST;
/* If existing session is in IP-encap tunnel, refuse new session */
if (session2->tunnel->encap == L2TP_ENCAPTYPE_IP)
return -EEXIST;
clist = session2->coll_list;
if (!clist) {
/* First collision. Allocate list to manage the collided sessions
* and add the existing session to the list.
*/
clist = kmalloc_obj(*clist, GFP_ATOMIC);
if (!clist)
return -ENOMEM;
spin_lock_init(&clist->lock);
INIT_LIST_HEAD(&clist->list);
refcount_set(&clist->ref_count, 1);
l2tp_session_coll_list_add(clist, session2);
}
/* If existing session isn't already in the session hlist, add it. */
if (!hash_hashed(&session2->hlist))
hash_add_rcu(pn->l2tp_v3_session_htable, &session2->hlist,
session2->hlist_key);
/* Add new session to the hlist and collision list */
hash_add_rcu(pn->l2tp_v3_session_htable, &session1->hlist,
session1->hlist_key);
refcount_inc(&clist->ref_count);
l2tp_session_coll_list_add(clist, session1);
return 0;
}
static void l2tp_session_collision_del(struct l2tp_net *pn,
struct l2tp_session *session)
{
struct l2tp_session_coll_list *clist = session->coll_list;
unsigned long session_key = session->session_id;
struct l2tp_session *session2;
lockdep_assert_held(&pn->l2tp_session_idr_lock);
hash_del_rcu(&session->hlist);
if (clist) {
/* Remove session from its collision list. If there
* are other sessions with the same ID, replace this
* session's IDR entry with that session, otherwise
* remove the IDR entry. If this is the last session,
* the collision list data is freed.
*/
spin_lock(&clist->lock);
list_del_init(&session->clist);
session2 = list_first_entry_or_null(&clist->list, struct l2tp_session, clist);
if (session2) {
void *old = idr_replace(&pn->l2tp_v3_session_idr, session2, session_key);
WARN_ON_ONCE(IS_ERR_VALUE(old));
} else {
void *removed = idr_remove(&pn->l2tp_v3_session_idr, session_key);
WARN_ON_ONCE(removed != session);
}
session->coll_list = NULL;
spin_unlock(&clist->lock);
if (refcount_dec_and_test(&clist->ref_count))
kfree(clist);
l2tp_session_put(session);
}
}
int l2tp_session_register(struct l2tp_session *session,
struct l2tp_tunnel *tunnel)
{
struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
struct l2tp_session *other_session = NULL;
void *old = NULL;
u32 session_key;
int err;
spin_lock_bh(&tunnel->list_lock);
spin_lock_bh(&pn->l2tp_session_idr_lock);
if (!tunnel->acpt_newsess) {
err = -ENODEV;
goto out;
}
if (tunnel->version == L2TP_HDR_VER_3) {
session_key = session->session_id;
err = idr_alloc_u32(&pn->l2tp_v3_session_idr, NULL,
&session_key, session_key, GFP_ATOMIC);
/* IP encap expects session IDs to be globally unique, while
* UDP encap doesn't. This isn't per the RFC, which says that
* sessions are identified only by the session ID, but is to
* support existing userspace which depends on it.
*/
if (err == -ENOSPC && tunnel->encap == L2TP_ENCAPTYPE_UDP) {
other_session = idr_find(&pn->l2tp_v3_session_idr,
session_key);
err = l2tp_session_collision_add(pn, session,
other_session);
}
} else {
session_key = l2tp_v2_session_key(tunnel->tunnel_id,
session->session_id);
err = idr_alloc_u32(&pn->l2tp_v2_session_idr, NULL,
&session_key, session_key, GFP_ATOMIC);
}
if (err) {
if (err == -ENOSPC)
err = -EEXIST;
goto out;
}
refcount_inc(&tunnel->ref_count);
WRITE_ONCE(session->tunnel, tunnel);
list_add_rcu(&session->list, &tunnel->session_list);
/* this makes session available to lockless getters */
if (tunnel->version == L2TP_HDR_VER_3) {
if (!other_session)
old = idr_replace(&pn->l2tp_v3_session_idr, session, session_key);
} else {
old = idr_replace(&pn->l2tp_v2_session_idr, session, session_key);
}
/* old should be NULL, unless something removed or modified
* the IDR entry after our idr_alloc_32 above (which shouldn't
* happen).
*/
WARN_ON_ONCE(old);
out:
spin_unlock_bh(&pn->l2tp_session_idr_lock);
spin_unlock_bh(&tunnel->list_lock);
if (!err)
trace_register_session(session);
return err;
}
EXPORT_SYMBOL_GPL(l2tp_session_register);
/*****************************************************************************
* Receive data handling
*****************************************************************************/
/* Queue a skb in order. We come here only if the skb has an L2TP sequence
* number.
*/
static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb)
{
struct sk_buff *skbp;
struct sk_buff *tmp;
u32 ns = L2TP_SKB_CB(skb)->ns;
spin_lock_bh(&session->reorder_q.lock);
skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
if (L2TP_SKB_CB(skbp)->ns > ns) {
__skb_queue_before(&session->reorder_q, skbp, skb);
atomic_long_inc(&session->stats.rx_oos_packets);
goto out;
}
}
__skb_queue_tail(&session->reorder_q, skb);
out:
spin_unlock_bh(&session->reorder_q.lock);
}
/* Dequeue a single skb.
*/
static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb)
{
struct l2tp_tunnel *tunnel = session->tunnel;
int length = L2TP_SKB_CB(skb)->length;
/* We're about to requeue the skb, so return resources
* to its current owner (a socket receive buffer).
*/
skb_orphan(skb);
atomic_long_inc(&tunnel->stats.rx_packets);
atomic_long_add(length, &tunnel->stats.rx_bytes);
atomic_long_inc(&session->stats.rx_packets);
atomic_long_add(length, &session->stats.rx_bytes);
if (L2TP_SKB_CB(skb)->has_seq) {
/* Bump our Nr */
session->nr++;
session->nr &= session->nr_max;
trace_session_seqnum_update(session);
}
/* call private receive handler */
if (session->recv_skb)
(*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
else
kfree_skb(skb);
}
/* Dequeue skbs from the session's reorder_q, subject to packet order.
* Skbs that have been in the queue for too long are simply discarded.
*/
static void l2tp_recv_dequeue(struct l2tp_session *session)
{
struct sk_buff *skb;
struct sk_buff *tmp;
/* If the pkt at the head of the queue has the nr that we
* expect to send up next, dequeue it and any other
* in-sequence packets behind it.
*/
start:
spin_lock_bh(&session->reorder_q.lock);
skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
struct l2tp_skb_cb *cb = L2TP_SKB_CB(skb);
/* If the packet has been pending on the queue for too long, discard it */
if (time_after(jiffies, cb->expires)) {
atomic_long_inc(&session->stats.rx_seq_discards);
atomic_long_inc(&session->stats.rx_errors);
trace_session_pkt_expired(session, cb->ns);
session->reorder_skip = 1;
__skb_unlink(skb, &session->reorder_q);
kfree_skb(skb);
continue;
}
if (cb->has_seq) {
if (session->reorder_skip) {
session->reorder_skip = 0;
session->nr = cb->ns;
trace_session_seqnum_reset(session);
}
if (cb->ns != session->nr)
goto out;
}
__skb_unlink(skb, &session->reorder_q);
/* Process the skb. We release the queue lock while we
* do so to let other contexts process the queue.
*/
spin_unlock_bh(&session->reorder_q.lock);
l2tp_recv_dequeue_skb(session, skb);
goto start;
}
out:
spin_unlock_bh(&session->reorder_q.lock);
}
static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr)
{
u32 nws;
if (nr >= session->nr)
nws = nr - session->nr;
else
nws = (session->nr_max + 1) - (session->nr - nr);
return nws < session->nr_window_size;
}
/* If packet has sequence numbers, queue it if acceptable. Returns 0 if
* acceptable, else non-zero.
*/
static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb)
{
struct l2tp_skb_cb *cb = L2TP_SKB_CB(skb);
if (!l2tp_seq_check_rx_window(session, cb->ns)) {
/* Packet sequence number is outside allowed window.
* Discard it.
*/
trace_session_pkt_outside_rx_window(session, cb->ns);
goto discard;
}
if (session->reorder_timeout != 0) {
/* Packet reordering enabled. Add skb to session's
* reorder queue, in order of ns.
*/
l2tp_recv_queue_skb(session, skb);
goto out;
}
/* Packet reordering disabled. Discard out-of-sequence packets, while
* tracking the number if in-sequence packets after the first OOS packet
* is seen. After nr_oos_count_max in-sequence packets, reset the
* sequence number to re-enable packet reception.
*/
if (cb->ns == session->nr) {
skb_queue_tail(&session->reorder_q, skb);
} else {
u32 nr_oos = cb->ns;
u32 nr_next = (session->nr_oos + 1) & session->nr_max;
if (nr_oos == nr_next)
session->nr_oos_count++;
else
session->nr_oos_count = 0;
session->nr_oos = nr_oos;
if (session->nr_oos_count > session->nr_oos_count_max) {
session->reorder_skip = 1;
}
if (!session->reorder_skip) {
atomic_long_inc(&session->stats.rx_seq_discards);
trace_session_pkt_oos(session, cb->ns);
goto discard;
}
skb_queue_tail(&session->reorder_q, skb);
}
out:
return 0;
discard:
return 1;
}
/* Do receive processing of L2TP data frames. We handle both L2TPv2
* and L2TPv3 data frames here.
*
* L2TPv2 Data Message Header
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Tunnel ID | Session ID |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Ns (opt) | Nr (opt) |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Offset Size (opt) | Offset pad... (opt)
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* Data frames are marked by T=0. All other fields are the same as
* those in L2TP control frames.
*
* L2TPv3 Data Message Header
*
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | L2TP Session Header |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | L2-Specific Sublayer |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Tunnel Payload ...
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* L2TPv3 Session Header Over IP
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Session ID |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Cookie (optional, maximum 64 bits)...
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* L2TPv3 L2-Specific Sublayer Format
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |x|S|x|x|x|x|x|x| Sequence Number |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* Cookie value and sublayer format are negotiated with the peer when
* the session is set up. Unlike L2TPv2, we do not need to parse the
* packet header to determine if optional fields are present.
*
* Caller must already have parsed the frame and determined that it is
* a data (not control) frame before coming here. Fields up to the
* session-id have already been parsed and ptr points to the data
* after the session-id.
*/
void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
unsigned char *ptr, unsigned char *optr, u16 hdrflags,
int length)
{
struct l2tp_tunnel *tunnel = session->tunnel;
int offset;
/* Parse and check optional cookie */
if (session->peer_cookie_len > 0) {
if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
pr_debug_ratelimited("%s: cookie mismatch (%u/%u). Discarding.\n",
tunnel->name, tunnel->tunnel_id,
session->session_id);
atomic_long_inc(&session->stats.rx_cookie_discards);
goto discard;
}
ptr += session->peer_cookie_len;
}
/* Handle the optional sequence numbers. Sequence numbers are
* in different places for L2TPv2 and L2TPv3.
*
* If we are the LAC, enable/disable sequence numbers under
* the control of the LNS. If no sequence numbers present but
* we were expecting them, discard frame.
*/
L2TP_SKB_CB(skb)->has_seq = 0;
if (tunnel->version == L2TP_HDR_VER_2) {
if (hdrflags & L2TP_HDRFLAG_S) {
/* Store L2TP info in the skb */
L2TP_SKB_CB(skb)->ns = ntohs(*(__be16 *)ptr);
L2TP_SKB_CB(skb)->has_seq = 1;
ptr += 2;
/* Skip past nr in the header */
ptr += 2;
}
} else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
u32 l2h = ntohl(*(__be32 *)ptr);
if (l2h & 0x40000000) {
/* Store L2TP info in the skb */
L2TP_SKB_CB(skb)->ns = l2h & 0x00ffffff;
L2TP_SKB_CB(skb)->has_seq = 1;
}
ptr += 4;
}
if (L2TP_SKB_CB(skb)->has_seq) {
/* Received a packet with sequence numbers. If we're the LAC,
* check if we sre sending sequence numbers and if not,
* configure it so.
*/
if (!session->lns_mode && !session->send_seq) {
trace_session_seqnum_lns_enable(session);
session->send_seq = 1;
l2tp_session_set_header_len(session, tunnel->version,
tunnel->encap);
}
} else {
/* No sequence numbers.
* If user has configured mandatory sequence numbers, discard.
*/
if (session->recv_seq) {
pr_debug_ratelimited("%s: recv data has no seq numbers when required. Discarding.\n",
session->name);
atomic_long_inc(&session->stats.rx_seq_discards);
goto discard;
}
/* If we're the LAC and we're sending sequence numbers, the
* LNS has requested that we no longer send sequence numbers.
* If we're the LNS and we're sending sequence numbers, the
* LAC is broken. Discard the frame.
*/
if (!session->lns_mode && session->send_seq) {
trace_session_seqnum_lns_disable(session);
session->send_seq = 0;
l2tp_session_set_header_len(session, tunnel->version,
tunnel->encap);
} else if (session->send_seq) {
pr_debug_ratelimited("%s: recv data has no seq numbers when required. Discarding.\n",
session->name);
atomic_long_inc(&session->stats.rx_seq_discards);
goto discard;
}
}
/* Session data offset is defined only for L2TPv2 and is
* indicated by an optional 16-bit value in the header.
*/
if (tunnel->version == L2TP_HDR_VER_2) {
/* If offset bit set, skip it. */
if (hdrflags & L2TP_HDRFLAG_O) {
offset = ntohs(*(__be16 *)ptr);
ptr += 2 + offset;
}
}
offset = ptr - optr;
if (!pskb_may_pull(skb, offset))
goto discard;
__skb_pull(skb, offset);
/* Prepare skb for adding to the session's reorder_q. Hold
* packets for max reorder_timeout or 1 second if not
* reordering.
*/
L2TP_SKB_CB(skb)->length = length;
L2TP_SKB_CB(skb)->expires = jiffies +
(session->reorder_timeout ? session->reorder_timeout : HZ);
/* Add packet to the session's receive queue. Reordering is done here, if
* enabled. Saved L2TP protocol info is stored in skb->sb[].
*/
if (L2TP_SKB_CB(skb)->has_seq) {
if (l2tp_recv_data_seq(session, skb))
goto discard;
} else {
/* No sequence numbers. Add the skb to the tail of the
* reorder queue. This ensures that it will be
* delivered after all previous sequenced skbs.
*/
skb_queue_tail(&session->reorder_q, skb);
}
/* Try to dequeue as many skbs from reorder_q as we can. */
l2tp_recv_dequeue(session);
return;
discard:
atomic_long_inc(&session->stats.rx_errors);
kfree_skb(skb);
}
EXPORT_SYMBOL_GPL(l2tp_recv_common);
/* Drop skbs from the session's reorder_q
*/
static void l2tp_session_queue_purge(struct l2tp_session *session)
{
struct sk_buff *skb = NULL;
while ((skb = skb_dequeue(&session->reorder_q))) {
atomic_long_inc(&session->stats.rx_errors);
kfree_skb(skb);
}
}
/* UDP encapsulation receive handler. See net/ipv4/udp.c for details. */
int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
{
struct l2tp_session *session = NULL;
struct l2tp_tunnel *tunnel = NULL;
struct net *net = sock_net(sk);
unsigned char *ptr, *optr;
u16 hdrflags;
u16 version;
int length;
/* UDP has verified checksum */
/* UDP always verifies the packet length. */
__skb_pull(skb, sizeof(struct udphdr));
/* Short packet? */
if (!pskb_may_pull(skb, L2TP_HDR_SIZE_MAX))
goto pass;
/* Point to L2TP header */
optr = skb->data;
ptr = skb->data;
/* Get L2TP header flags */
hdrflags = ntohs(*(__be16 *)ptr);
/* Get protocol version */
version = hdrflags & L2TP_HDR_VER_MASK;
/* Get length of L2TP packet */
length = skb->len;
/* If type is control packet, it is handled by userspace. */
if (hdrflags & L2TP_HDRFLAG_T)
goto pass;
/* Skip flags */
ptr += 2;
if (version == L2TP_HDR_VER_2) {
u16 tunnel_id, session_id;
/* If length is present, skip it */
if (hdrflags & L2TP_HDRFLAG_L)
ptr += 2;
/* Extract tunnel and session ID */
tunnel_id = ntohs(*(__be16 *)ptr);
ptr += 2;
session_id = ntohs(*(__be16 *)ptr);
ptr += 2;
session = l2tp_v2_session_get(net, tunnel_id, session_id);
} else {
u32 session_id;
ptr += 2; /* skip reserved bits */
session_id = ntohl(*(__be32 *)ptr);
ptr += 4;
session = l2tp_v3_session_get(net, sk, session_id);
}
if (!session || !session->recv_skb) {
if (session)
l2tp_session_put(session);
/* Not found? Pass to userspace to deal with */
goto pass;
}
tunnel = session->tunnel;
/* Check protocol version */
if (version != tunnel->version) {
l2tp_session_put(session);
goto invalid;
}
if (version == L2TP_HDR_VER_3 &&
l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr)) {
l2tp_session_put(session);
goto invalid;
}
l2tp_recv_common(session, skb, ptr, optr, hdrflags, length);
l2tp_session_put(session);
return 0;
invalid:
atomic_long_inc(&tunnel->stats.rx_invalid);
pass:
/* Put UDP header back */
__skb_push(skb, sizeof(struct udphdr));
return 1;
}
EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
/* UDP encapsulation receive error handler. See net/ipv4/udp.c for details. */
static void l2tp_udp_encap_err_recv(struct sock *sk, struct sk_buff *skb, int err,
__be16 port, u32 info, u8 *payload)
{
sk->sk_err = err;
sk_error_report(sk);
if (ip_hdr(skb)->version == IPVERSION) {
if (inet_test_bit(RECVERR, sk))
return ip_icmp_error(sk, skb, err, port, info, payload);
#if IS_ENABLED(CONFIG_IPV6)
} else {
if (inet6_test_bit(RECVERR6, sk))
return ipv6_icmp_error(sk, skb, err, port, info, payload);
#endif
}
}
/************************************************************************
* Transmit handling
***********************************************************************/
/* Build an L2TP header for the session into the buffer provided.
*/
static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
{
struct l2tp_tunnel *tunnel = session->tunnel;
__be16 *bufp = buf;
__be16 *optr = buf;
u16 flags = L2TP_HDR_VER_2;
u32 tunnel_id = tunnel->peer_tunnel_id;
u32 session_id = session->peer_session_id;
if (session->send_seq)
flags |= L2TP_HDRFLAG_S;
/* Setup L2TP header. */
*bufp++ = htons(flags);
*bufp++ = htons(tunnel_id);
*bufp++ = htons(session_id);
if (session->send_seq) {
*bufp++ = htons(session->ns);
*bufp++ = 0;
session->ns++;
session->ns &= 0xffff;
trace_session_seqnum_update(session);
}
return bufp - optr;
}
static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
{
struct l2tp_tunnel *tunnel = session->tunnel;
char *bufp = buf;
char *optr = bufp;
/* Setup L2TP header. The header differs slightly for UDP and
* IP encapsulations. For UDP, there is 4 bytes of flags.
*/
if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
u16 flags = L2TP_HDR_VER_3;
*((__be16 *)bufp) = htons(flags);
bufp += 2;
*((__be16 *)bufp) = 0;
bufp += 2;
}
*((__be32 *)bufp) = htonl(session->peer_session_id);
bufp += 4;
if (session->cookie_len) {
memcpy(bufp, &session->cookie[0], session->cookie_len);
bufp += session->cookie_len;
}
if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
u32 l2h = 0;
if (session->send_seq) {
l2h = 0x40000000 | session->ns;
session->ns++;
session->ns &= 0xffffff;
trace_session_seqnum_update(session);
}
*((__be32 *)bufp) = htonl(l2h);
bufp += 4;
}
return bufp - optr;
}
/* Queue the packet to IP for output: tunnel socket lock must be held */
static int l2tp_xmit_queue(struct l2tp_tunnel *tunnel, struct sk_buff *skb, struct flowi *fl)
{
int err;
skb->ignore_df = 1;
skb_dst_drop(skb);
#if IS_ENABLED(CONFIG_IPV6)
if (l2tp_sk_is_v6(tunnel->sock))
err = inet6_csk_xmit(tunnel->sock, skb, NULL);
else
#endif
err = ip_queue_xmit(tunnel->sock, skb, fl);
return err >= 0 ? NET_XMIT_SUCCESS : NET_XMIT_DROP;
}
static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, unsigned int *len)
{
struct l2tp_tunnel *tunnel = session->tunnel;
unsigned int data_len = skb->len;
struct sock *sk = tunnel->sock;
int headroom, uhlen, udp_len;
int ret = NET_XMIT_SUCCESS;
struct inet_sock *inet;
struct udphdr *uh;
/* Check that there's enough headroom in the skb to insert IP,
* UDP and L2TP headers. If not enough, expand it to
* make room. Adjust truesize.
*/
uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(*uh) : 0;
headroom = NET_SKB_PAD + sizeof(struct iphdr) + uhlen + session->hdr_len;
if (skb_cow_head(skb, headroom)) {
kfree_skb(skb);
return NET_XMIT_DROP;
}
/* Setup L2TP header */
if (tunnel->version == L2TP_HDR_VER_2)
l2tp_build_l2tpv2_header(session, __skb_push(skb, session->hdr_len));
else
l2tp_build_l2tpv3_header(session, __skb_push(skb, session->hdr_len));
/* Reset control buffer */
memset(skb->cb, 0, sizeof(skb->cb));
nf_reset_ct(skb);
/* L2TP uses its own lockdep subclass to avoid lockdep splats caused by
* nested socket calls on the same lockdep socket class. This can
* happen when data from a user socket is routed over l2tp, which uses
* another userspace socket.
*/
spin_lock_nested(&sk->sk_lock.slock, L2TP_DEPTH_NESTING);
if (sock_owned_by_user(sk)) {
kfree_skb(skb);
ret = NET_XMIT_DROP;
goto out_unlock;
}
/* The user-space may change the connection status for the user-space
* provided socket at run time: we must check it under the socket lock
*/
if (tunnel->fd >= 0 && sk->sk_state != TCP_ESTABLISHED) {
kfree_skb(skb);
ret = NET_XMIT_DROP;
goto out_unlock;
}
/* Report transmitted length before we add encap header, which keeps
* statistics consistent for both UDP and IP encap tx/rx paths.
*/
*len = skb->len;
inet = inet_sk(sk);
switch (tunnel->encap) {
case L2TP_ENCAPTYPE_UDP:
/* Setup UDP header */
__skb_push(skb, sizeof(*uh));
skb_reset_transport_header(skb);
uh = udp_hdr(skb);
uh->source = inet->inet_sport;
uh->dest = inet->inet_dport;
udp_len = uhlen + session->hdr_len + data_len;
if (udp_len > U16_MAX) {
kfree_skb(skb);
ret = NET_XMIT_DROP;
goto out_unlock;
}
udp_set_len_short(uh, udp_len);
/* Calculate UDP checksum if configured to do so */
#if IS_ENABLED(CONFIG_IPV6)
if (l2tp_sk_is_v6(sk))
udp6_set_csum(udp_get_no_check6_tx(sk),
skb, &inet6_sk(sk)->saddr,
&sk->sk_v6_daddr, udp_len);
else
#endif
udp_set_csum(sk->sk_no_check_tx, skb, inet->inet_saddr,
inet->inet_daddr, udp_len);
break;
case L2TP_ENCAPTYPE_IP:
break;
}
ret = l2tp_xmit_queue(tunnel, skb, &inet->cork.fl);
out_unlock:
spin_unlock(&sk->sk_lock.slock);
return ret;
}
/* If caller requires the skb to have a ppp header, the header must be
* inserted in the skb data before calling this function.
*/
int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb)
{
unsigned int len = 0;
int ret;
ret = l2tp_xmit_core(session, skb, &len);
if (ret == NET_XMIT_SUCCESS) {
atomic_long_inc(&session->tunnel->stats.tx_packets);
atomic_long_add(len, &session->tunnel->stats.tx_bytes);
atomic_long_inc(&session->stats.tx_packets);
atomic_long_add(len, &session->stats.tx_bytes);
} else {
atomic_long_inc(&session->tunnel->stats.tx_errors);
atomic_long_inc(&session->stats.tx_errors);
}
return ret;
}
EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
/*****************************************************************************
* Tinnel and session create/destroy.
*****************************************************************************/
/* Remove an l2tp session from l2tp_core's lists. */
static void l2tp_session_unhash(struct l2tp_session *session)
{
struct l2tp_tunnel *tunnel = session->tunnel;
if (tunnel) {
struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
struct l2tp_session *removed = session;
spin_lock_bh(&tunnel->list_lock);
spin_lock_bh(&pn->l2tp_session_idr_lock);
/* Remove from the per-tunnel list */
list_del_rcu(&session->list);
/* Remove from per-net IDR */
if (tunnel->version == L2TP_HDR_VER_3) {
if (hash_hashed(&session->hlist))
l2tp_session_collision_del(pn, session);
else
removed = idr_remove(&pn->l2tp_v3_session_idr,
session->session_id);
} else {
u32 session_key = l2tp_v2_session_key(tunnel->tunnel_id,
session->session_id);
removed = idr_remove(&pn->l2tp_v2_session_idr,
session_key);
}
WARN_ON_ONCE(removed && removed != session);
spin_unlock_bh(&pn->l2tp_session_idr_lock);
spin_unlock_bh(&tunnel->list_lock);
}
}
/* When the tunnel is closed, all the attached sessions need to go too.
*/
static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
{
struct l2tp_session *session;
spin_lock_bh(&tunnel->list_lock);
tunnel->acpt_newsess = false;
list_for_each_entry(session, &tunnel->session_list, list)
l2tp_session_delete(session);
spin_unlock_bh(&tunnel->list_lock);
}
/* Tunnel socket destroy hook for UDP encapsulation */
static void l2tp_udp_encap_destroy(struct sock *sk)
{
struct l2tp_tunnel *tunnel;
tunnel = l2tp_sk_to_tunnel(sk);
if (tunnel) {
l2tp_tunnel_delete(tunnel);
l2tp_tunnel_put(tunnel);
}
}
static void l2tp_tunnel_remove(struct net *net, struct l2tp_tunnel *tunnel)
{
struct l2tp_net *pn = l2tp_pernet(net);
spin_lock_bh(&pn->l2tp_tunnel_idr_lock);
idr_remove(&pn->l2tp_tunnel_idr, tunnel->tunnel_id);
spin_unlock_bh(&pn->l2tp_tunnel_idr_lock);
}
/* Workqueue tunnel deletion function */
static void l2tp_tunnel_del_work(struct work_struct *work)
{
struct l2tp_tunnel *tunnel = container_of(work, struct l2tp_tunnel,
del_work);
l2tp_tunnel_closeall(tunnel);
/* If the tunnel socket was created within the kernel, use
* the sk API to release it here.
*/
if (tunnel->fd < 0) {
struct socket *sock = tunnel->sock->sk_socket;
if (sock) {
kernel_sock_shutdown(sock, SHUT_RDWR);
sock_release(sock);
}
}
l2tp_tunnel_remove(tunnel->l2tp_net, tunnel);
/* drop initial ref */
l2tp_tunnel_put(tunnel);
/* drop workqueue ref */
l2tp_tunnel_put(tunnel);
}
/* Create a socket for the tunnel, if one isn't set up by
* userspace. This is used for static tunnels where there is no
* managing L2TP daemon.
*
* Since we don't want these sockets to keep a namespace alive by
* themselves, we drop the socket's namespace refcount after creation.
* These sockets are freed when the namespace exits using the pernet
* exit hook.
*/
static int l2tp_tunnel_sock_create(struct net *net,
u32 tunnel_id,
u32 peer_tunnel_id,
struct l2tp_tunnel_cfg *cfg,
struct socket **sockp)
{
int err = -EINVAL;
struct socket *sock = NULL;
struct udp_port_cfg udp_conf;
switch (cfg->encap) {
case L2TP_ENCAPTYPE_UDP:
memset(&udp_conf, 0, sizeof(udp_conf));
#if IS_ENABLED(CONFIG_IPV6)
if (cfg->local_ip6 && cfg->peer_ip6) {
udp_conf.family = AF_INET6;
memcpy(&udp_conf.local_ip6, cfg->local_ip6,
sizeof(udp_conf.local_ip6));
memcpy(&udp_conf.peer_ip6, cfg->peer_ip6,
sizeof(udp_conf.peer_ip6));
udp_conf.use_udp6_tx_checksums =
!cfg->udp6_zero_tx_checksums;
udp_conf.use_udp6_rx_checksums =
!cfg->udp6_zero_rx_checksums;
} else
#endif
{
udp_conf.family = AF_INET;
udp_conf.local_ip = cfg->local_ip;
udp_conf.peer_ip = cfg->peer_ip;
udp_conf.use_udp_checksums = cfg->use_udp_checksums;
}
udp_conf.local_udp_port = htons(cfg->local_udp_port);
udp_conf.peer_udp_port = htons(cfg->peer_udp_port);
err = udp_sock_create(net, &udp_conf, &sock);
if (err < 0)
goto out;
break;
case L2TP_ENCAPTYPE_IP:
#if IS_ENABLED(CONFIG_IPV6)
if (cfg->local_ip6 && cfg->peer_ip6) {
struct sockaddr_l2tpip6 ip6_addr = {0};
err = sock_create_kern(net, AF_INET6, SOCK_DGRAM,
IPPROTO_L2TP, &sock);
if (err < 0)
goto out;
ip6_addr.l2tp_family = AF_INET6;
memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6,
sizeof(ip6_addr.l2tp_addr));
ip6_addr.l2tp_conn_id = tunnel_id;
err = kernel_bind(sock, (struct sockaddr_unsized *)&ip6_addr,
sizeof(ip6_addr));
if (err < 0)
goto out;
ip6_addr.l2tp_family = AF_INET6;
memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6,
sizeof(ip6_addr.l2tp_addr));
ip6_addr.l2tp_conn_id = peer_tunnel_id;
err = kernel_connect(sock,
(struct sockaddr_unsized *)&ip6_addr,
sizeof(ip6_addr), 0);
if (err < 0)
goto out;
} else
#endif
{
struct sockaddr_l2tpip ip_addr = {0};
err = sock_create_kern(net, AF_INET, SOCK_DGRAM,
IPPROTO_L2TP, &sock);
if (err < 0)
goto out;
ip_addr.l2tp_family = AF_INET;
ip_addr.l2tp_addr = cfg->local_ip;
ip_addr.l2tp_conn_id = tunnel_id;
err = kernel_bind(sock, (struct sockaddr_unsized *)&ip_addr,
sizeof(ip_addr));
if (err < 0)
goto out;
ip_addr.l2tp_family = AF_INET;
ip_addr.l2tp_addr = cfg->peer_ip;
ip_addr.l2tp_conn_id = peer_tunnel_id;
err = kernel_connect(sock, (struct sockaddr_unsized *)&ip_addr,
sizeof(ip_addr), 0);
if (err < 0)
goto out;
}
break;
default:
goto out;
}
out:
*sockp = sock;
if (err < 0 && sock) {
kernel_sock_shutdown(sock, SHUT_RDWR);
sock_release(sock);
*sockp = NULL;
}
return err;
}
int l2tp_tunnel_create(int fd, int version, u32 tunnel_id, u32 peer_tunnel_id,
struct l2tp_tunnel_cfg *cfg, struct l2tp_tunnel **tunnelp)
{
struct l2tp_tunnel *tunnel = NULL;
int err;
enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
if (cfg)
encap = cfg->encap;
tunnel = kzalloc_obj(*tunnel);
if (!tunnel) {
err = -ENOMEM;
goto err;
}
tunnel->version = version;
tunnel->tunnel_id = tunnel_id;
tunnel->peer_tunnel_id = peer_tunnel_id;
sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
spin_lock_init(&tunnel->list_lock);
tunnel->acpt_newsess = true;
INIT_LIST_HEAD(&tunnel->session_list);
tunnel->encap = encap;
refcount_set(&tunnel->ref_count, 1);
tunnel->fd = fd;
/* Init delete workqueue struct */
INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work);
err = 0;
err:
if (tunnelp)
*tunnelp = tunnel;
return err;
}
EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
static int l2tp_validate_socket(const struct sock *sk, const struct net *net,
enum l2tp_encap_type encap)
{
struct l2tp_tunnel *tunnel;
if (!net_eq(sock_net(sk), net))
return -EINVAL;
if (sk->sk_type != SOCK_DGRAM)
return -EPROTONOSUPPORT;
if (sk->sk_family != PF_INET && sk->sk_family != PF_INET6)
return -EPROTONOSUPPORT;
if ((encap == L2TP_ENCAPTYPE_UDP && sk->sk_protocol != IPPROTO_UDP) ||
(encap == L2TP_ENCAPTYPE_IP && sk->sk_protocol != IPPROTO_L2TP))
return -EPROTONOSUPPORT;
if (encap == L2TP_ENCAPTYPE_UDP && sk->sk_user_data)
return -EBUSY;
tunnel = l2tp_sk_to_tunnel(sk);
if (tunnel) {
l2tp_tunnel_put(tunnel);
return -EBUSY;
}
return 0;
}
int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net,
struct l2tp_tunnel_cfg *cfg)
{
struct l2tp_net *pn = l2tp_pernet(net);
u32 tunnel_id = tunnel->tunnel_id;
struct socket *sock;
struct sock *sk;
int ret;
spin_lock_bh(&pn->l2tp_tunnel_idr_lock);
ret = idr_alloc_u32(&pn->l2tp_tunnel_idr, NULL, &tunnel_id, tunnel_id,
GFP_ATOMIC);
spin_unlock_bh(&pn->l2tp_tunnel_idr_lock);
if (ret)
return ret == -ENOSPC ? -EEXIST : ret;
if (tunnel->fd < 0) {
ret = l2tp_tunnel_sock_create(net, tunnel->tunnel_id,
tunnel->peer_tunnel_id, cfg,
&sock);
if (ret < 0)
goto err;
} else {
sock = sockfd_lookup(tunnel->fd, &ret);
if (!sock)
goto err;
}
sk = sock->sk;
lock_sock(sk);
write_lock_bh(&sk->sk_callback_lock);
ret = l2tp_validate_socket(sk, net, tunnel->encap);
if (ret < 0)
goto err_inval_sock;
write_unlock_bh(&sk->sk_callback_lock);
if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
struct udp_tunnel_sock_cfg udp_cfg = {
.encap_type = UDP_ENCAP_L2TPINUDP,
.encap_rcv = l2tp_udp_encap_recv,
.encap_err_rcv = l2tp_udp_encap_err_recv,
.encap_destroy = l2tp_udp_encap_destroy,
};
setup_udp_tunnel_sock(net, sock->sk, &udp_cfg);
}
sk->sk_allocation = GFP_ATOMIC;
release_sock(sk);
sock_hold(sk);
tunnel->sock = sk;
tunnel->l2tp_net = net;
spin_lock_bh(&pn->l2tp_tunnel_idr_lock);
idr_replace(&pn->l2tp_tunnel_idr, tunnel, tunnel->tunnel_id);
spin_unlock_bh(&pn->l2tp_tunnel_idr_lock);
trace_register_tunnel(tunnel);
if (tunnel->fd >= 0)
sockfd_put(sock);
return 0;
err_inval_sock:
write_unlock_bh(&sk->sk_callback_lock);
release_sock(sk);
if (tunnel->fd < 0)
sock_release(sock);
else
sockfd_put(sock);
err:
l2tp_tunnel_remove(net, tunnel);
return ret;
}
EXPORT_SYMBOL_GPL(l2tp_tunnel_register);
/* This function is used by the netlink TUNNEL_DELETE command.
*/
void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
{
if (!test_and_set_bit(0, &tunnel->dead)) {
trace_delete_tunnel(tunnel);
refcount_inc(&tunnel->ref_count);
queue_work(l2tp_wq, &tunnel->del_work);
}
}
EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
void l2tp_session_delete(struct l2tp_session *session)
{
if (!test_and_set_bit(0, &session->dead)) {
trace_delete_session(session);
refcount_inc(&session->ref_count);
queue_work(l2tp_wq, &session->del_work);
}
}
EXPORT_SYMBOL_GPL(l2tp_session_delete);
/* Workqueue session deletion function */
static void l2tp_session_del_work(struct work_struct *work)
{
struct l2tp_session *session = container_of(work, struct l2tp_session,
del_work);
l2tp_session_unhash(session);
l2tp_session_queue_purge(session);
if (session->session_close)
(*session->session_close)(session);
/* drop initial ref */
l2tp_session_put(session);
/* drop workqueue ref */
l2tp_session_put(session);
}
/* We come here whenever a session's send_seq, cookie_len or
* l2specific_type parameters are set.
*/
void l2tp_session_set_header_len(struct l2tp_session *session, int version,
enum l2tp_encap_type encap)
{
if (version == L2TP_HDR_VER_2) {
session->hdr_len = 6;
if (session->send_seq)
session->hdr_len += 4;
} else {
session->hdr_len = 4 + session->cookie_len;
session->hdr_len += l2tp_get_l2specific_len(session);
if (encap == L2TP_ENCAPTYPE_UDP)
session->hdr_len += 4;
}
}
EXPORT_SYMBOL_GPL(l2tp_session_set_header_len);
struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id,
u32 peer_session_id, struct l2tp_session_cfg *cfg)
{
struct l2tp_session *session;
session = kzalloc(sizeof(*session) + priv_size, GFP_KERNEL);
if (session) {
session->magic = L2TP_SESSION_MAGIC;
session->session_id = session_id;
session->peer_session_id = peer_session_id;
session->nr = 0;
if (tunnel->version == L2TP_HDR_VER_2)
session->nr_max = 0xffff;
else
session->nr_max = 0xffffff;
session->nr_window_size = session->nr_max / 2;
session->nr_oos_count_max = 4;
/* Use NR of first received packet */
session->reorder_skip = 1;
sprintf(&session->name[0], "sess %u/%u",
tunnel->tunnel_id, session->session_id);
skb_queue_head_init(&session->reorder_q);
session->hlist_key = l2tp_v3_session_hashkey(tunnel->sock, session->session_id);
INIT_HLIST_NODE(&session->hlist);
INIT_LIST_HEAD(&session->clist);
INIT_LIST_HEAD(&session->list);
INIT_WORK(&session->del_work, l2tp_session_del_work);
if (cfg) {
session->pwtype = cfg->pw_type;
session->send_seq = cfg->send_seq;
session->recv_seq = cfg->recv_seq;
session->lns_mode = cfg->lns_mode;
session->reorder_timeout = cfg->reorder_timeout;
session->l2specific_type = cfg->l2specific_type;
session->cookie_len = cfg->cookie_len;
memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len);
session->peer_cookie_len = cfg->peer_cookie_len;
memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
}
l2tp_session_set_header_len(session, tunnel->version, tunnel->encap);
refcount_set(&session->ref_count, 1);
return session;
}
return ERR_PTR(-ENOMEM);
}
EXPORT_SYMBOL_GPL(l2tp_session_create);
/*****************************************************************************
* Init and cleanup
*****************************************************************************/
static __net_init int l2tp_init_net(struct net *net)
{
struct l2tp_net *pn = net_generic(net, l2tp_net_id);
idr_init(&pn->l2tp_tunnel_idr);
spin_lock_init(&pn->l2tp_tunnel_idr_lock);
idr_init(&pn->l2tp_v2_session_idr);
idr_init(&pn->l2tp_v3_session_idr);
spin_lock_init(&pn->l2tp_session_idr_lock);
return 0;
}
static __net_exit void l2tp_pre_exit_net(struct net *net)
{
struct l2tp_net *pn = l2tp_pernet(net);
struct l2tp_tunnel *tunnel = NULL;
unsigned long tunnel_id, tmp;
rcu_read_lock_bh();
idr_for_each_entry_ul(&pn->l2tp_tunnel_idr, tunnel, tmp, tunnel_id) {
if (tunnel)
l2tp_tunnel_delete(tunnel);
}
rcu_read_unlock_bh();
if (l2tp_wq) {
/* Run all TUNNEL_DELETE work items just queued. */
__flush_workqueue(l2tp_wq);
/* Each TUNNEL_DELETE work item will queue a SESSION_DELETE
* work item for each session in the tunnel. Flush the
* workqueue again to process these.
*/
__flush_workqueue(l2tp_wq);
}
}
static int l2tp_idr_item_unexpected(int id, void *p, void *data)
{
const char *idr_name = data;
pr_err("l2tp: %s IDR not empty at net %d exit\n", idr_name, id);
WARN_ON_ONCE(1);
return 1;
}
static __net_exit void l2tp_exit_net(struct net *net)
{
struct l2tp_net *pn = l2tp_pernet(net);
/* Our per-net IDRs should be empty. Check that is so, to
* help catch cleanup races or refcnt leaks.
*/
idr_for_each(&pn->l2tp_v2_session_idr, l2tp_idr_item_unexpected,
"v2_session");
idr_for_each(&pn->l2tp_v3_session_idr, l2tp_idr_item_unexpected,
"v3_session");
idr_for_each(&pn->l2tp_tunnel_idr, l2tp_idr_item_unexpected,
"tunnel");
idr_destroy(&pn->l2tp_v2_session_idr);
idr_destroy(&pn->l2tp_v3_session_idr);
idr_destroy(&pn->l2tp_tunnel_idr);
}
static struct pernet_operations l2tp_net_ops = {
.init = l2tp_init_net,
.exit = l2tp_exit_net,
.pre_exit = l2tp_pre_exit_net,
.id = &l2tp_net_id,
.size = sizeof(struct l2tp_net),
};
static int __init l2tp_init(void)
{
int rc = 0;
rc = register_pernet_device(&l2tp_net_ops);
if (rc)
goto out;
l2tp_wq = alloc_workqueue("l2tp", WQ_UNBOUND, 0);
if (!l2tp_wq) {
pr_err("alloc_workqueue failed\n");
unregister_pernet_device(&l2tp_net_ops);
rc = -ENOMEM;
goto out;
}
pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION);
out:
return rc;
}
static void __exit l2tp_exit(void)
{
unregister_pernet_device(&l2tp_net_ops);
if (l2tp_wq) {
destroy_workqueue(l2tp_wq);
l2tp_wq = NULL;
}
}
module_init(l2tp_init);
module_exit(l2tp_exit);
MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
MODULE_DESCRIPTION("L2TP core");
MODULE_LICENSE("GPL");
MODULE_VERSION(L2TP_DRV_VERSION);
