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l2tp: lookup tunnel from socket without using sk_user_data

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l2tp_sk_to_tunnel derives the tunnel from sk_user_data. Instead,
lookup the tunnel by walking the tunnel IDR for a tunnel using the
indicated sock. This is slow but l2tp_sk_to_tunnel is not used in
the datapath so performance isn't critical.

l2tp_tunnel_destruct needs a variant of l2tp_sk_to_tunnel which does
not bump the tunnel refcount since the tunnel refcount is already 0.

Change l2tp_sk_to_tunnel sk arg to const since it does not modify sk.

Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
James Chapman 2024-07-29 16:38:00 +01:00 committed by David S. Miller
parent 0a658d088c
commit 2e7a280692
4 changed files with 54 additions and 17 deletions
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52
net/l2tp/l2tp_core.c
View File

@ -150,15 +150,43 @@ static void l2tp_session_free(struct l2tp_session *session)
kfree(session);
}
struct l2tp_tunnel *l2tp_sk_to_tunnel(struct sock *sk)
static struct l2tp_tunnel *__l2tp_sk_to_tunnel(const struct sock *sk)
{
struct l2tp_tunnel *tunnel = sk->sk_user_data;
const struct net *net = sock_net(sk);
unsigned long tunnel_id, tmp;
struct l2tp_tunnel *tunnel;
struct l2tp_net *pn;
if (tunnel)
if (WARN_ON(tunnel->magic != L2TP_TUNNEL_MAGIC))
return NULL;
WARN_ON_ONCE(!rcu_read_lock_bh_held());
pn = l2tp_pernet(net);
idr_for_each_entry_ul(&pn->l2tp_tunnel_idr, tunnel, tmp, tunnel_id) {
if (tunnel && tunnel->sock == sk)
return tunnel;
}
return tunnel;
return NULL;
}
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);
@ -1213,8 +1241,10 @@ EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
*/
static void l2tp_tunnel_destruct(struct sock *sk)
{
struct l2tp_tunnel *tunnel = l2tp_sk_to_tunnel(sk);
struct l2tp_tunnel *tunnel;
rcu_read_lock_bh();
tunnel = __l2tp_sk_to_tunnel(sk);
if (!tunnel)
goto end;
@ -1242,6 +1272,7 @@ static void l2tp_tunnel_destruct(struct sock *sk)
kfree_rcu(tunnel, rcu);
end:
rcu_read_unlock_bh();
return;
}
@ -1308,10 +1339,13 @@ static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
/* 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);
struct l2tp_tunnel *tunnel;
if (tunnel)
tunnel = l2tp_sk_to_tunnel(sk);
if (tunnel) {
l2tp_tunnel_delete(tunnel);
l2tp_tunnel_dec_refcount(tunnel);
}
}
static void l2tp_tunnel_remove(struct net *net, struct l2tp_tunnel *tunnel)

5
net/l2tp/l2tp_core.h
View File

@ -273,10 +273,7 @@ void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
/* IOCTL helper for IP encap modules. */
int l2tp_ioctl(struct sock *sk, int cmd, int *karg);
/* Extract the tunnel structure from a socket's sk_user_data pointer,
* validating the tunnel magic feather.
*/
struct l2tp_tunnel *l2tp_sk_to_tunnel(struct sock *sk);
struct l2tp_tunnel *l2tp_sk_to_tunnel(const struct sock *sk);
static inline int l2tp_get_l2specific_len(struct l2tp_session *session)
{

7
net/l2tp/l2tp_ip.c
View File

@ -235,14 +235,17 @@ static void l2tp_ip_close(struct sock *sk, long timeout)
static void l2tp_ip_destroy_sock(struct sock *sk)
{
struct l2tp_tunnel *tunnel = l2tp_sk_to_tunnel(sk);
struct l2tp_tunnel *tunnel;
struct sk_buff *skb;
while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
kfree_skb(skb);
if (tunnel)
tunnel = l2tp_sk_to_tunnel(sk);
if (tunnel) {
l2tp_tunnel_delete(tunnel);
l2tp_tunnel_dec_refcount(tunnel);
}
}
static int l2tp_ip_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)

7
net/l2tp/l2tp_ip6.c
View File

@ -246,14 +246,17 @@ static void l2tp_ip6_close(struct sock *sk, long timeout)
static void l2tp_ip6_destroy_sock(struct sock *sk)
{
struct l2tp_tunnel *tunnel = l2tp_sk_to_tunnel(sk);
struct l2tp_tunnel *tunnel;
lock_sock(sk);
ip6_flush_pending_frames(sk);
release_sock(sk);
if (tunnel)
tunnel = l2tp_sk_to_tunnel(sk);
if (tunnel) {
l2tp_tunnel_delete(tunnel);
l2tp_tunnel_dec_refcount(tunnel);
}
}
static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)