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Message-Id: <efd2d6f1479ae42ee867fae3119af1bc80ea23ed.1718877398.git.jchapman@katalix.com>
Date: Thu, 20 Jun 2024 12:22:39 +0100
From: James Chapman <jchapman@...alix.com>
To: netdev@...r.kernel.org
Cc: gnault@...hat.com,
samuel.thibault@...-lyon.org,
ridge.kennedy@...iedtelesis.co.nz
Subject: [PATCH net-next 3/8] l2tp: store l2tpv2 sessions in per-net IDR
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@...alix.com>
Reviewed-by: Tom Parkin <tparkin@...alix.com>
---
net/l2tp/l2tp_core.c | 70 ++++++++++++++++++++++++++++++++++----------
net/l2tp/l2tp_core.h | 1 +
2 files changed, 56 insertions(+), 15 deletions(-)
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index d6bffdb16466..6f30b347fd46 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -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);
}
diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index bfccc4ca2644..d80f15f5b9fc 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -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);
--
2.34.1
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