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espintcp: remove encap socket caching to avoid reference leak

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[ Upstream commit 028363685bd0b7a19b4a820f82dd905b1dc83999 ]

The current scheme for caching the encap socket can lead to reference
leaks when we try to delete the netns.

The reference chain is: xfrm_state -> enacp_sk -> netns

Since the encap socket is a userspace socket, it holds a reference on
the netns. If we delete the espintcp state (through flush or
individual delete) before removing the netns, the reference on the
socket is dropped and the netns is correctly deleted. Otherwise, the
netns may not be reachable anymore (if all processes within the ns
have terminated), so we cannot delete the xfrm state to drop its
reference on the socket.

This patch results in a small (~2% in my tests) performance
regression.

A GC-type mechanism could be added for the socket cache, to clear
references if the state hasn't been used "recently", but it's a lot
more complex than just not caching the socket.

Fixes: e27cca96cd ("xfrm: add espintcp (RFC 8229)")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Sabrina Dubroca
2025-04-09 15:59:57 +02:00
committed by Greg Kroah-Hartman
parent 3cf3d4f112
commit b58a295d10
4 changed files with 8 additions and 94 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
include/net/xfrm.h
View File

@@ -228,7 +228,6 @@ struct xfrm_state {
/* Data for encapsulator */
struct xfrm_encap_tmpl *encap;
struct sock __rcu *encap_sk;
/* Data for care-of address */
xfrm_address_t *coaddr;

49
net/ipv4/esp4.c
View File

@@ -118,47 +118,16 @@ static void esp_ssg_unref(struct xfrm_state *x, void *tmp, struct sk_buff *skb)
}
#ifdef CONFIG_INET_ESPINTCP
struct esp_tcp_sk {
struct sock *sk;
struct rcu_head rcu;
};
static void esp_free_tcp_sk(struct rcu_head *head)
{
struct esp_tcp_sk *esk = container_of(head, struct esp_tcp_sk, rcu);
sock_put(esk->sk);
kfree(esk);
}
static struct sock *esp_find_tcp_sk(struct xfrm_state *x)
{
struct xfrm_encap_tmpl *encap = x->encap;
struct net *net = xs_net(x);
struct esp_tcp_sk *esk;
__be16 sport, dport;
struct sock *nsk;
struct sock *sk;
sk = rcu_dereference(x->encap_sk);
if (sk && sk->sk_state == TCP_ESTABLISHED)
return sk;
spin_lock_bh(&x->lock);
sport = encap->encap_sport;
dport = encap->encap_dport;
nsk = rcu_dereference_protected(x->encap_sk,
lockdep_is_held(&x->lock));
if (sk && sk == nsk) {
esk = kmalloc(sizeof(*esk), GFP_ATOMIC);
if (!esk) {
spin_unlock_bh(&x->lock);
return ERR_PTR(-ENOMEM);
}
RCU_INIT_POINTER(x->encap_sk, NULL);
esk->sk = sk;
call_rcu(&esk->rcu, esp_free_tcp_sk);
}
spin_unlock_bh(&x->lock);
sk = inet_lookup_established(net, net->ipv4.tcp_death_row.hashinfo, x->id.daddr.a4,
@@ -171,20 +140,6 @@ static struct sock *esp_find_tcp_sk(struct xfrm_state *x)
return ERR_PTR(-EINVAL);
}
spin_lock_bh(&x->lock);
nsk = rcu_dereference_protected(x->encap_sk,
lockdep_is_held(&x->lock));
if (encap->encap_sport != sport ||
encap->encap_dport != dport) {
sock_put(sk);
sk = nsk ?: ERR_PTR(-EREMCHG);
} else if (sk == nsk) {
sock_put(sk);
} else {
rcu_assign_pointer(x->encap_sk, sk);
}
spin_unlock_bh(&x->lock);
return sk;
}
@@ -207,6 +162,8 @@ static int esp_output_tcp_finish(struct xfrm_state *x, struct sk_buff *skb)
err = espintcp_push_skb(sk, skb);
bh_unlock_sock(sk);
sock_put(sk);
out:
rcu_read_unlock();
return err;
@@ -391,6 +348,8 @@ static struct ip_esp_hdr *esp_output_tcp_encap(struct xfrm_state *x,
if (IS_ERR(sk))
return ERR_CAST(sk);
sock_put(sk);
*lenp = htons(len);
esph = (struct ip_esp_hdr *)(lenp + 1);

49
net/ipv6/esp6.c
View File

@@ -135,47 +135,16 @@ static void esp_ssg_unref(struct xfrm_state *x, void *tmp, struct sk_buff *skb)
}
#ifdef CONFIG_INET6_ESPINTCP
struct esp_tcp_sk {
struct sock *sk;
struct rcu_head rcu;
};
static void esp_free_tcp_sk(struct rcu_head *head)
{
struct esp_tcp_sk *esk = container_of(head, struct esp_tcp_sk, rcu);
sock_put(esk->sk);
kfree(esk);
}
static struct sock *esp6_find_tcp_sk(struct xfrm_state *x)
{
struct xfrm_encap_tmpl *encap = x->encap;
struct net *net = xs_net(x);
struct esp_tcp_sk *esk;
__be16 sport, dport;
struct sock *nsk;
struct sock *sk;
sk = rcu_dereference(x->encap_sk);
if (sk && sk->sk_state == TCP_ESTABLISHED)
return sk;
spin_lock_bh(&x->lock);
sport = encap->encap_sport;
dport = encap->encap_dport;
nsk = rcu_dereference_protected(x->encap_sk,
lockdep_is_held(&x->lock));
if (sk && sk == nsk) {
esk = kmalloc(sizeof(*esk), GFP_ATOMIC);
if (!esk) {
spin_unlock_bh(&x->lock);
return ERR_PTR(-ENOMEM);
}
RCU_INIT_POINTER(x->encap_sk, NULL);
esk->sk = sk;
call_rcu(&esk->rcu, esp_free_tcp_sk);
}
spin_unlock_bh(&x->lock);
sk = __inet6_lookup_established(net, net->ipv4.tcp_death_row.hashinfo, &x->id.daddr.in6,
@@ -188,20 +157,6 @@ static struct sock *esp6_find_tcp_sk(struct xfrm_state *x)
return ERR_PTR(-EINVAL);
}
spin_lock_bh(&x->lock);
nsk = rcu_dereference_protected(x->encap_sk,
lockdep_is_held(&x->lock));
if (encap->encap_sport != sport ||
encap->encap_dport != dport) {
sock_put(sk);
sk = nsk ?: ERR_PTR(-EREMCHG);
} else if (sk == nsk) {
sock_put(sk);
} else {
rcu_assign_pointer(x->encap_sk, sk);
}
spin_unlock_bh(&x->lock);
return sk;
}
@@ -224,6 +179,8 @@ static int esp_output_tcp_finish(struct xfrm_state *x, struct sk_buff *skb)
err = espintcp_push_skb(sk, skb);
bh_unlock_sock(sk);
sock_put(sk);
out:
rcu_read_unlock();
return err;
@@ -427,6 +384,8 @@ static struct ip_esp_hdr *esp6_output_tcp_encap(struct xfrm_state *x,
if (IS_ERR(sk))
return ERR_CAST(sk);
sock_put(sk);
*lenp = htons(len);
esph = (struct ip_esp_hdr *)(lenp + 1);

3
net/xfrm/xfrm_state.c
View File

@@ -754,9 +754,6 @@ int __xfrm_state_delete(struct xfrm_state *x)
net->xfrm.state_num--;
spin_unlock(&net->xfrm.xfrm_state_lock);
if (x->encap_sk)
sock_put(rcu_dereference_raw(x->encap_sk));
xfrm_dev_state_delete(x);
/* All xfrm_state objects are created by xfrm_state_alloc.