linux-stable/net/l2tp/l2tp_core.c
Tom Parkin 07b8ca3792 net/l2tp: convert tunnel rwlock_t to rcu
Previously commit e02d494d2c ("l2tp: Convert rwlock to RCU") converted
most, but not all, rwlock instances in the l2tp subsystem to RCU.

The remaining rwlock protects the per-tunnel hashlist of sessions which
is used for session lookups in the UDP-encap data path.

Convert the remaining rwlock to rcu to improve performance of UDP-encap
tunnels.

Note that the tunnel and session, which both live on RCU-protected
lists, use slightly different approaches to incrementing their refcounts
in the various getter functions.

The tunnel has to use refcount_inc_not_zero because the tunnel shutdown
process involves dropping the refcount to zero prior to synchronizing
RCU readers (via. kfree_rcu).

By contrast, the session shutdown removes the session from the list(s)
it is on, synchronizes with readers, and then decrements the session
refcount.  Since the getter functions increment the session refcount
with the RCU read lock held we prevent getters seeing a zero session
refcount, and therefore don't need to use refcount_inc_not_zero.

Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-11-29 12:11:25 +00:00

1717 lines
45 KiB
C

// 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/hash.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"
#include "trace.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
/* 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 {
struct list_head l2tp_tunnel_list;
/* Lock for write access to l2tp_tunnel_list */
spinlock_t l2tp_tunnel_list_lock;
struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
/* Lock for write access to l2tp_session_hlist */
spinlock_t l2tp_session_hlist_lock;
};
#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 inline struct l2tp_net *l2tp_pernet(const struct net *net)
{
return net_generic(net, l2tp_net_id);
}
/* Session hash global list for L2TPv3.
* The session_id SHOULD be random according to RFC3931, but several
* L2TP implementations use incrementing session_ids. So we do a real
* hash on the session_id, rather than a simple bitmask.
*/
static inline struct hlist_head *
l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id)
{
return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)];
}
/* Session hash list.
* The session_id SHOULD be random according to RFC2661, but several
* L2TP implementations (Cisco and Microsoft) use incrementing
* session_ids. So we do a real hash on the session_id, rather than a
* simple bitmask.
*/
static inline struct hlist_head *
l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
{
return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
}
static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
{
trace_free_tunnel(tunnel);
sock_put(tunnel->sock);
/* the tunnel is freed in the socket destructor */
}
static void l2tp_session_free(struct l2tp_session *session)
{
trace_free_session(session);
if (session->tunnel)
l2tp_tunnel_dec_refcount(session->tunnel);
kfree(session);
}
struct l2tp_tunnel *l2tp_sk_to_tunnel(struct sock *sk)
{
struct l2tp_tunnel *tunnel = sk->sk_user_data;
if (tunnel)
if (WARN_ON(tunnel->magic != L2TP_TUNNEL_MAGIC))
return NULL;
return tunnel;
}
EXPORT_SYMBOL_GPL(l2tp_sk_to_tunnel);
void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel)
{
refcount_inc(&tunnel->ref_count);
}
EXPORT_SYMBOL_GPL(l2tp_tunnel_inc_refcount);
void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel)
{
if (refcount_dec_and_test(&tunnel->ref_count))
l2tp_tunnel_free(tunnel);
}
EXPORT_SYMBOL_GPL(l2tp_tunnel_dec_refcount);
void l2tp_session_inc_refcount(struct l2tp_session *session)
{
refcount_inc(&session->ref_count);
}
EXPORT_SYMBOL_GPL(l2tp_session_inc_refcount);
void l2tp_session_dec_refcount(struct l2tp_session *session)
{
if (refcount_dec_and_test(&session->ref_count))
l2tp_session_free(session);
}
EXPORT_SYMBOL_GPL(l2tp_session_dec_refcount);
/* 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();
list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
if (tunnel->tunnel_id == tunnel_id &&
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_nth(const struct net *net, int nth)
{
const struct l2tp_net *pn = l2tp_pernet(net);
struct l2tp_tunnel *tunnel;
int count = 0;
rcu_read_lock_bh();
list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
if (++count > nth &&
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_nth);
struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel,
u32 session_id)
{
struct hlist_head *session_list;
struct l2tp_session *session;
session_list = l2tp_session_id_hash(tunnel, session_id);
rcu_read_lock_bh();
hlist_for_each_entry_rcu(session, session_list, hlist)
if (session->session_id == session_id) {
l2tp_session_inc_refcount(session);
rcu_read_unlock_bh();
return session;
}
rcu_read_unlock_bh();
return NULL;
}
EXPORT_SYMBOL_GPL(l2tp_tunnel_get_session);
struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id)
{
struct hlist_head *session_list;
struct l2tp_session *session;
session_list = l2tp_session_id_hash_2(l2tp_pernet(net), session_id);
rcu_read_lock_bh();
hlist_for_each_entry_rcu(session, session_list, global_hlist)
if (session->session_id == session_id) {
l2tp_session_inc_refcount(session);
rcu_read_unlock_bh();
return session;
}
rcu_read_unlock_bh();
return NULL;
}
EXPORT_SYMBOL_GPL(l2tp_session_get);
struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth)
{
int hash;
struct l2tp_session *session;
int count = 0;
rcu_read_lock_bh();
for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
hlist_for_each_entry_rcu(session, &tunnel->session_hlist[hash], hlist) {
if (++count > nth) {
l2tp_session_inc_refcount(session);
rcu_read_unlock_bh();
return session;
}
}
}
rcu_read_unlock_bh();
return NULL;
}
EXPORT_SYMBOL_GPL(l2tp_session_get_nth);
/* 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);
int hash;
struct l2tp_session *session;
rcu_read_lock_bh();
for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) {
if (!strcmp(session->ifname, ifname)) {
l2tp_session_inc_refcount(session);
rcu_read_unlock_bh();
return session;
}
}
}
rcu_read_unlock_bh();
return NULL;
}
EXPORT_SYMBOL_GPL(l2tp_session_get_by_ifname);
int l2tp_session_register(struct l2tp_session *session,
struct l2tp_tunnel *tunnel)
{
struct l2tp_session *session_walk;
struct hlist_head *g_head;
struct hlist_head *head;
struct l2tp_net *pn;
int err;
head = l2tp_session_id_hash(tunnel, session->session_id);
spin_lock_bh(&tunnel->hlist_lock);
if (!tunnel->acpt_newsess) {
err = -ENODEV;
goto err_tlock;
}
hlist_for_each_entry(session_walk, head, hlist)
if (session_walk->session_id == session->session_id) {
err = -EEXIST;
goto err_tlock;
}
if (tunnel->version == L2TP_HDR_VER_3) {
pn = l2tp_pernet(tunnel->l2tp_net);
g_head = l2tp_session_id_hash_2(pn, session->session_id);
spin_lock_bh(&pn->l2tp_session_hlist_lock);
/* IP encap expects session IDs to be globally unique, while
* UDP encap doesn't.
*/
hlist_for_each_entry(session_walk, g_head, global_hlist)
if (session_walk->session_id == session->session_id &&
(session_walk->tunnel->encap == L2TP_ENCAPTYPE_IP ||
tunnel->encap == L2TP_ENCAPTYPE_IP)) {
err = -EEXIST;
goto err_tlock_pnlock;
}
l2tp_tunnel_inc_refcount(tunnel);
hlist_add_head_rcu(&session->global_hlist, g_head);
spin_unlock_bh(&pn->l2tp_session_hlist_lock);
} else {
l2tp_tunnel_inc_refcount(tunnel);
}
hlist_add_head_rcu(&session->hlist, head);
spin_unlock_bh(&tunnel->hlist_lock);
trace_register_session(session);
return 0;
err_tlock_pnlock:
spin_unlock_bh(&pn->l2tp_session_hlist_lock);
err_tlock:
spin_unlock_bh(&tunnel->hlist_lock);
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);
}
} 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);
} 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);
}
}
/* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
* here. The skb is not on a list when we get here.
* Returns 0 if the packet was a data packet and was successfully passed on.
* Returns 1 if the packet was not a good data packet and could not be
* forwarded. All such packets are passed up to userspace to deal with.
*/
static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb)
{
struct l2tp_session *session = NULL;
unsigned char *ptr, *optr;
u16 hdrflags;
u32 tunnel_id, session_id;
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)) {
pr_debug_ratelimited("%s: recv short packet (len=%d)\n",
tunnel->name, skb->len);
goto invalid;
}
/* Point to L2TP header */
optr = skb->data;
ptr = skb->data;
/* Get L2TP header flags */
hdrflags = ntohs(*(__be16 *)ptr);
/* Check protocol version */
version = hdrflags & L2TP_HDR_VER_MASK;
if (version != tunnel->version) {
pr_debug_ratelimited("%s: recv protocol version mismatch: got %d expected %d\n",
tunnel->name, version, tunnel->version);
goto invalid;
}
/* 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 (tunnel->version == L2TP_HDR_VER_2) {
/* 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;
} else {
ptr += 2; /* skip reserved bits */
tunnel_id = tunnel->tunnel_id;
session_id = ntohl(*(__be32 *)ptr);
ptr += 4;
}
/* Find the session context */
session = l2tp_tunnel_get_session(tunnel, session_id);
if (!session || !session->recv_skb) {
if (session)
l2tp_session_dec_refcount(session);
/* Not found? Pass to userspace to deal with */
pr_debug_ratelimited("%s: no session found (%u/%u). Passing up.\n",
tunnel->name, tunnel_id, session_id);
goto pass;
}
if (tunnel->version == L2TP_HDR_VER_3 &&
l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr)) {
l2tp_session_dec_refcount(session);
goto invalid;
}
l2tp_recv_common(session, skb, ptr, optr, hdrflags, length);
l2tp_session_dec_refcount(session);
return 0;
invalid:
atomic_long_inc(&tunnel->stats.rx_invalid);
pass:
/* Put UDP header back */
__skb_push(skb, sizeof(struct udphdr));
return 1;
}
/* UDP encapsulation receive handler. See net/ipv4/udp.c.
* Return codes:
* 0 : success.
* <0: error
* >0: skb should be passed up to userspace as UDP.
*/
int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
{
struct l2tp_tunnel *tunnel;
/* Note that this is called from the encap_rcv hook inside an
* RCU-protected region, but without the socket being locked.
* Hence we use rcu_dereference_sk_user_data to access the
* tunnel data structure rather the usual l2tp_sk_to_tunnel
* accessor function.
*/
tunnel = rcu_dereference_sk_user_data(sk);
if (!tunnel)
goto pass_up;
if (WARN_ON(tunnel->magic != L2TP_TUNNEL_MAGIC))
goto pass_up;
if (l2tp_udp_recv_core(tunnel, skb))
goto pass_up;
return 0;
pass_up:
return 1;
}
EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
/************************************************************************
* 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 skb netfilter state */
memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | IPSKB_REROUTED);
nf_reset_ct(skb);
bh_lock_sock(sk);
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;
uh->len = htons(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:
bh_unlock_sock(sk);
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.
*****************************************************************************/
/* Tunnel socket destruct hook.
* The tunnel context is deleted only when all session sockets have been
* closed.
*/
static void l2tp_tunnel_destruct(struct sock *sk)
{
struct l2tp_tunnel *tunnel = l2tp_sk_to_tunnel(sk);
if (!tunnel)
goto end;
/* Disable udp encapsulation */
switch (tunnel->encap) {
case L2TP_ENCAPTYPE_UDP:
/* No longer an encapsulation socket. See net/ipv4/udp.c */
(udp_sk(sk))->encap_type = 0;
(udp_sk(sk))->encap_rcv = NULL;
(udp_sk(sk))->encap_destroy = NULL;
break;
case L2TP_ENCAPTYPE_IP:
break;
}
/* Remove hooks into tunnel socket */
sk->sk_destruct = tunnel->old_sk_destruct;
sk->sk_user_data = NULL;
/* Call the original destructor */
if (sk->sk_destruct)
(*sk->sk_destruct)(sk);
kfree_rcu(tunnel, rcu);
end:
return;
}
/* Remove an l2tp session from l2tp_core's hash lists. */
static void l2tp_session_unhash(struct l2tp_session *session)
{
struct l2tp_tunnel *tunnel = session->tunnel;
/* Remove the session from core hashes */
if (tunnel) {
/* Remove from the per-tunnel hash */
spin_lock_bh(&tunnel->hlist_lock);
hlist_del_init_rcu(&session->hlist);
spin_unlock_bh(&tunnel->hlist_lock);
/* For L2TPv3 we have a per-net hash: remove from there, too */
if (tunnel->version != L2TP_HDR_VER_2) {
struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
spin_lock_bh(&pn->l2tp_session_hlist_lock);
hlist_del_init_rcu(&session->global_hlist);
spin_unlock_bh(&pn->l2tp_session_hlist_lock);
}
synchronize_rcu();
}
}
/* 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;
int hash;
spin_lock_bh(&tunnel->hlist_lock);
tunnel->acpt_newsess = false;
for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
again:
hlist_for_each_entry_rcu(session, &tunnel->session_hlist[hash], hlist) {
hlist_del_init_rcu(&session->hlist);
spin_unlock_bh(&tunnel->hlist_lock);
l2tp_session_delete(session);
spin_lock_bh(&tunnel->hlist_lock);
/* Now restart from the beginning of this hash
* chain. We always remove a session from the
* list so we are guaranteed to make forward
* progress.
*/
goto again;
}
}
spin_unlock_bh(&tunnel->hlist_lock);
}
/* Tunnel socket destroy hook for UDP encapsulation */
static void l2tp_udp_encap_destroy(struct sock *sk)
{
struct l2tp_tunnel *tunnel = l2tp_sk_to_tunnel(sk);
if (tunnel)
l2tp_tunnel_delete(tunnel);
}
/* 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);
struct sock *sk = tunnel->sock;
struct socket *sock = sk->sk_socket;
struct l2tp_net *pn;
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) {
if (sock) {
kernel_sock_shutdown(sock, SHUT_RDWR);
sock_release(sock);
}
}
/* Remove the tunnel struct from the tunnel list */
pn = l2tp_pernet(tunnel->l2tp_net);
spin_lock_bh(&pn->l2tp_tunnel_list_lock);
list_del_rcu(&tunnel->list);
spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
/* drop initial ref */
l2tp_tunnel_dec_refcount(tunnel);
/* drop workqueue ref */
l2tp_tunnel_dec_refcount(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 *)&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 *)&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 *)&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 *)&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;
}
static struct lock_class_key l2tp_socket_class;
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(sizeof(*tunnel), GFP_KERNEL);
if (!tunnel) {
err = -ENOMEM;
goto err;
}
tunnel->version = version;
tunnel->tunnel_id = tunnel_id;
tunnel->peer_tunnel_id = peer_tunnel_id;
tunnel->magic = L2TP_TUNNEL_MAGIC;
sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
spin_lock_init(&tunnel->hlist_lock);
tunnel->acpt_newsess = true;
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);
INIT_LIST_HEAD(&tunnel->list);
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)
{
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 (sk->sk_user_data)
return -EBUSY;
return 0;
}
int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net,
struct l2tp_tunnel_cfg *cfg)
{
struct l2tp_tunnel *tunnel_walk;
struct l2tp_net *pn;
struct socket *sock;
struct sock *sk;
int 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;
ret = l2tp_validate_socket(sock->sk, net, tunnel->encap);
if (ret < 0)
goto err_sock;
}
tunnel->l2tp_net = net;
pn = l2tp_pernet(net);
sk = sock->sk;
sock_hold(sk);
tunnel->sock = sk;
spin_lock_bh(&pn->l2tp_tunnel_list_lock);
list_for_each_entry(tunnel_walk, &pn->l2tp_tunnel_list, list) {
if (tunnel_walk->tunnel_id == tunnel->tunnel_id) {
spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
sock_put(sk);
ret = -EEXIST;
goto err_sock;
}
}
list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
struct udp_tunnel_sock_cfg udp_cfg = {
.sk_user_data = tunnel,
.encap_type = UDP_ENCAP_L2TPINUDP,
.encap_rcv = l2tp_udp_encap_recv,
.encap_destroy = l2tp_udp_encap_destroy,
};
setup_udp_tunnel_sock(net, sock, &udp_cfg);
} else {
sk->sk_user_data = tunnel;
}
tunnel->old_sk_destruct = sk->sk_destruct;
sk->sk_destruct = &l2tp_tunnel_destruct;
lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class,
"l2tp_sock");
sk->sk_allocation = GFP_ATOMIC;
trace_register_tunnel(tunnel);
if (tunnel->fd >= 0)
sockfd_put(sock);
return 0;
err_sock:
if (tunnel->fd < 0)
sock_release(sock);
else
sockfd_put(sock);
err:
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);
l2tp_tunnel_inc_refcount(tunnel);
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))
return;
trace_delete_session(session);
l2tp_session_unhash(session);
l2tp_session_queue_purge(session);
if (session->session_close)
(*session->session_close)(session);
l2tp_session_dec_refcount(session);
}
EXPORT_SYMBOL_GPL(l2tp_session_delete);
/* 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)
{
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 (session->tunnel->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->tunnel = tunnel;
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);
INIT_HLIST_NODE(&session->hlist);
INIT_HLIST_NODE(&session->global_hlist);
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);
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);
int hash;
INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
spin_lock_init(&pn->l2tp_tunnel_list_lock);
for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
spin_lock_init(&pn->l2tp_session_hlist_lock);
return 0;
}
static __net_exit void l2tp_exit_net(struct net *net)
{
struct l2tp_net *pn = l2tp_pernet(net);
struct l2tp_tunnel *tunnel = NULL;
int hash;
rcu_read_lock_bh();
list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
l2tp_tunnel_delete(tunnel);
}
rcu_read_unlock_bh();
if (l2tp_wq)
flush_workqueue(l2tp_wq);
rcu_barrier();
for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
WARN_ON_ONCE(!hlist_empty(&pn->l2tp_session_hlist[hash]));
}
static struct pernet_operations l2tp_net_ops = {
.init = l2tp_init_net,
.exit = l2tp_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);