mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2025-04-12 06:49:52 +00:00
Code Issues Packages Projects Releases Wiki Activity

l2tp: store l2tpv2 sessions in per-net IDR

Browse Source 
L2TPv2 sessions are currently kept in a per-tunnel hashlist, keyed by
16-bit session_id. When handling received L2TPv2 packets, we need to
first derive the tunnel using the 16-bit tunnel_id or sock, then
lookup the session in a per-tunnel hlist using the 16-bit session_id.

We want to avoid using sk_user_data in the datapath and double lookups
on every packet. So instead, use a per-net IDR to hold L2TPv2
sessions, keyed by a 32-bit value derived from the 16-bit tunnel_id
and session_id. This will allow the L2TPv2 UDP receive datapath to
lookup a session with a single lookup without deriving the tunnel
first.

L2TPv2 sessions are held in their own IDR to avoid potential
key collisions with L2TPv3 sessions.

Signed-off-by: James Chapman <jchapman@katalix.com>
Reviewed-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
James Chapman 2024-06-20 12:22:39 +01:00 committed by David S. Miller
parent aa5e17e1f5
commit 2a3339f6c9
2 changed files with 56 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

70
net/l2tp/l2tp_core.c
View File

@ -107,12 +107,18 @@ 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_v3_session_idr/htable */
/* 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 inline u32 l2tp_v2_session_key(u16 tunnel_id, u16 session_id)
{
return ((u32)tunnel_id) << 16 | session_id;
}
static inline unsigned long l2tp_v3_session_hashkey(struct sock *sk, u32 session_id)
{
return ((unsigned long)sk) + session_id;
@ -292,6 +298,24 @@ struct l2tp_session *l2tp_v3_session_get(const struct net *net, struct sock *sk,
}
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_nth(struct l2tp_tunnel *tunnel, int nth)
{
int hash;
@ -477,23 +501,32 @@ int l2tp_session_register(struct l2tp_session *session,
err = l2tp_session_collision_add(pn, session, session2);
}
spin_unlock_bh(&pn->l2tp_session_idr_lock);
if (err == -ENOSPC)
err = -EEXIST;
} else {
session_key = l2tp_v2_session_key(tunnel->tunnel_id,
session->session_id);
spin_lock_bh(&pn->l2tp_session_idr_lock);
err = idr_alloc_u32(&pn->l2tp_v2_session_idr, NULL,
&session_key, session_key, GFP_ATOMIC);
spin_unlock_bh(&pn->l2tp_session_idr_lock);
}
if (err)
if (err) {
if (err == -ENOSPC)
err = -EEXIST;
goto err_tlock;
}
l2tp_tunnel_inc_refcount(tunnel);
hlist_add_head_rcu(&session->hlist, head);
spin_unlock_bh(&tunnel->hlist_lock);
if (tunnel->version == L2TP_HDR_VER_3) {
spin_lock_bh(&pn->l2tp_session_idr_lock);
spin_lock_bh(&pn->l2tp_session_idr_lock);
if (tunnel->version == L2TP_HDR_VER_3)
idr_replace(&pn->l2tp_v3_session_idr, session, session_key);
spin_unlock_bh(&pn->l2tp_session_idr_lock);
}
else
idr_replace(&pn->l2tp_v2_session_idr, session, session_key);
spin_unlock_bh(&pn->l2tp_session_idr_lock);
trace_register_session(session);
@ -1321,25 +1354,30 @@ static void l2tp_session_unhash(struct l2tp_session *session)
/* Remove the session from core hashes */
if (tunnel) {
struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
struct l2tp_session *removed = session;
/* 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 IDR: remove from there, too */
/* Remove from per-net IDR */
spin_lock_bh(&pn->l2tp_session_idr_lock);
if (tunnel->version == L2TP_HDR_VER_3) {
struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
struct l2tp_session *removed = session;
spin_lock_bh(&pn->l2tp_session_idr_lock);
if (hash_hashed(&session->hlist))
l2tp_session_collision_del(pn, session);
else
removed = idr_remove(&pn->l2tp_v3_session_idr,
session->session_id);
WARN_ON_ONCE(removed && removed != session);
spin_unlock_bh(&pn->l2tp_session_idr_lock);
} 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);
synchronize_rcu();
}
@ -1802,6 +1840,7 @@ static __net_init int l2tp_init_net(struct net *net)
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);
@ -1825,6 +1864,7 @@ static __net_exit void l2tp_exit_net(struct net *net)
flush_workqueue(l2tp_wq);
rcu_barrier();
idr_destroy(&pn->l2tp_v2_session_idr);
idr_destroy(&pn->l2tp_v3_session_idr);
idr_destroy(&pn->l2tp_tunnel_idr);
}

1
net/l2tp/l2tp_core.h
View File

@ -231,6 +231,7 @@ struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel,
u32 session_id);
struct l2tp_session *l2tp_v3_session_get(const struct net *net, struct sock *sk, u32 session_id);
struct l2tp_session *l2tp_v2_session_get(const struct net *net, u16 tunnel_id, u16 session_id);
struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth);
struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
const char *ifname);