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Message-ID: <20251028033812.2043964-13-kuniyu@google.com>
Date: Tue, 28 Oct 2025 03:37:07 +0000
From: Kuniyuki Iwashima <kuniyu@...gle.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: Simon Horman <horms@...nel.org>, Kuniyuki Iwashima <kuniyu@...gle.com>,
Kuniyuki Iwashima <kuni1840@...il.com>, netdev@...r.kernel.org
Subject: [PATCH v1 net-next 12/13] mpls: Protect net->mpls.platform_label with
a per-netns mutex.
MPLS (re)uses RTNL to protect net->mpls.platform_label,
but the lock does not need to be RTNL at all.
Let's protect net->mpls.platform_label with a dedicated
per-netns mutex.
Signed-off-by: Kuniyuki Iwashima <kuniyu@...gle.com>
---
include/net/netns/mpls.h | 1 +
net/mpls/af_mpls.c | 55 ++++++++++++++++++++++++++--------------
net/mpls/internal.h | 7 ++++-
3 files changed, 43 insertions(+), 20 deletions(-)
diff --git a/include/net/netns/mpls.h b/include/net/netns/mpls.h
index 19ad2574b267..6682e51513ef 100644
--- a/include/net/netns/mpls.h
+++ b/include/net/netns/mpls.h
@@ -16,6 +16,7 @@ struct netns_mpls {
int default_ttl;
size_t platform_labels;
struct mpls_route __rcu * __rcu *platform_label;
+ struct mutex platform_mutex;
struct ctl_table_header *ctl;
};
diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index ffd8bc96be55..afe5b0b70b23 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -79,8 +79,8 @@ static struct mpls_route *mpls_route_input(struct net *net, unsigned int index)
{
struct mpls_route __rcu **platform_label;
- platform_label = rtnl_dereference(net->mpls.platform_label);
- return rtnl_dereference(platform_label[index]);
+ platform_label = mpls_dereference(net, net->mpls.platform_label);
+ return mpls_dereference(net, platform_label[index]);
}
static struct mpls_route *mpls_route_input_rcu(struct net *net, unsigned int index)
@@ -578,10 +578,8 @@ static void mpls_route_update(struct net *net, unsigned index,
struct mpls_route __rcu **platform_label;
struct mpls_route *rt;
- ASSERT_RTNL();
-
- platform_label = rtnl_dereference(net->mpls.platform_label);
- rt = rtnl_dereference(platform_label[index]);
+ platform_label = mpls_dereference(net, net->mpls.platform_label);
+ rt = mpls_dereference(net, platform_label[index]);
rcu_assign_pointer(platform_label[index], new);
mpls_notify_route(net, index, rt, new, info);
@@ -1472,8 +1470,6 @@ static struct mpls_dev *mpls_add_dev(struct net_device *dev)
int err = -ENOMEM;
int i;
- ASSERT_RTNL();
-
mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
if (!mdev)
return ERR_PTR(err);
@@ -1633,6 +1629,8 @@ static int mpls_dev_notify(struct notifier_block *this, unsigned long event,
unsigned int flags;
int err;
+ mutex_lock(&net->mpls.platform_mutex);
+
if (event == NETDEV_REGISTER) {
mdev = mpls_add_dev(dev);
if (IS_ERR(mdev)) {
@@ -1695,9 +1693,11 @@ static int mpls_dev_notify(struct notifier_block *this, unsigned long event,
}
out:
+ mutex_unlock(&net->mpls.platform_mutex);
return NOTIFY_OK;
err:
+ mutex_unlock(&net->mpls.platform_mutex);
return notifier_from_errno(err);
}
@@ -1973,6 +1973,7 @@ static int rtm_to_route_config(struct sk_buff *skb,
static int mpls_rtm_delroute(struct sk_buff *skb, struct nlmsghdr *nlh,
struct netlink_ext_ack *extack)
{
+ struct net *net = sock_net(skb->sk);
struct mpls_route_config *cfg;
int err;
@@ -1984,7 +1985,9 @@ static int mpls_rtm_delroute(struct sk_buff *skb, struct nlmsghdr *nlh,
if (err < 0)
goto out;
+ mutex_lock(&net->mpls.platform_mutex);
err = mpls_route_del(cfg, extack);
+ mutex_unlock(&net->mpls.platform_mutex);
out:
kfree(cfg);
@@ -1995,6 +1998,7 @@ static int mpls_rtm_delroute(struct sk_buff *skb, struct nlmsghdr *nlh,
static int mpls_rtm_newroute(struct sk_buff *skb, struct nlmsghdr *nlh,
struct netlink_ext_ack *extack)
{
+ struct net *net = sock_net(skb->sk);
struct mpls_route_config *cfg;
int err;
@@ -2006,7 +2010,9 @@ static int mpls_rtm_newroute(struct sk_buff *skb, struct nlmsghdr *nlh,
if (err < 0)
goto out;
+ mutex_lock(&net->mpls.platform_mutex);
err = mpls_route_add(cfg, extack);
+ mutex_unlock(&net->mpls.platform_mutex);
out:
kfree(cfg);
@@ -2407,6 +2413,8 @@ static int mpls_getroute(struct sk_buff *in_skb, struct nlmsghdr *in_nlh,
u8 n_labels;
int err;
+ mutex_lock(&net->mpls.platform_mutex);
+
err = mpls_valid_getroute_req(in_skb, in_nlh, tb, extack);
if (err < 0)
goto errout;
@@ -2450,7 +2458,8 @@ static int mpls_getroute(struct sk_buff *in_skb, struct nlmsghdr *in_nlh,
goto errout_free;
}
- return rtnl_unicast(skb, net, portid);
+ err = rtnl_unicast(skb, net, portid);
+ goto errout;
}
if (tb[RTA_NEWDST]) {
@@ -2542,12 +2551,14 @@ static int mpls_getroute(struct sk_buff *in_skb, struct nlmsghdr *in_nlh,
err = rtnl_unicast(skb, net, portid);
errout:
+ mutex_unlock(&net->mpls.platform_mutex);
return err;
nla_put_failure:
nlmsg_cancel(skb, nlh);
err = -EMSGSIZE;
errout_free:
+ mutex_unlock(&net->mpls.platform_mutex);
kfree_skb(skb);
return err;
}
@@ -2603,9 +2614,10 @@ static int resize_platform_label_table(struct net *net, size_t limit)
lo->addr_len);
}
- rtnl_lock();
+ mutex_lock(&net->mpls.platform_mutex);
+
/* Remember the original table */
- old = rtnl_dereference(net->mpls.platform_label);
+ old = mpls_dereference(net, net->mpls.platform_label);
old_limit = net->mpls.platform_labels;
/* Free any labels beyond the new table */
@@ -2636,7 +2648,7 @@ static int resize_platform_label_table(struct net *net, size_t limit)
net->mpls.platform_labels = limit;
rcu_assign_pointer(net->mpls.platform_label, labels);
- rtnl_unlock();
+ mutex_unlock(&net->mpls.platform_mutex);
mpls_rt_free(rt2);
mpls_rt_free(rt0);
@@ -2709,12 +2721,13 @@ static const struct ctl_table mpls_table[] = {
},
};
-static int mpls_net_init(struct net *net)
+static __net_init int mpls_net_init(struct net *net)
{
size_t table_size = ARRAY_SIZE(mpls_table);
struct ctl_table *table;
int i;
+ mutex_init(&net->mpls.platform_mutex);
net->mpls.platform_labels = 0;
net->mpls.platform_label = NULL;
net->mpls.ip_ttl_propagate = 1;
@@ -2740,7 +2753,7 @@ static int mpls_net_init(struct net *net)
return 0;
}
-static void mpls_net_exit(struct net *net)
+static __net_exit void mpls_net_exit(struct net *net)
{
struct mpls_route __rcu **platform_label;
size_t platform_labels;
@@ -2760,16 +2773,20 @@ static void mpls_net_exit(struct net *net)
* As such no additional rcu synchronization is necessary when
* freeing the platform_label table.
*/
- rtnl_lock();
- platform_label = rtnl_dereference(net->mpls.platform_label);
+ mutex_lock(&net->mpls.platform_mutex);
+
+ platform_label = mpls_dereference(net, net->mpls.platform_label);
platform_labels = net->mpls.platform_labels;
+
for (index = 0; index < platform_labels; index++) {
- struct mpls_route *rt = rtnl_dereference(platform_label[index]);
- RCU_INIT_POINTER(platform_label[index], NULL);
+ struct mpls_route *rt;
+
+ rt = mpls_dereference(net, platform_label[index]);
mpls_notify_route(net, index, rt, NULL, NULL);
mpls_rt_free(rt);
}
- rtnl_unlock();
+
+ mutex_unlock(&net->mpls.platform_mutex);
kvfree(platform_label);
}
diff --git a/net/mpls/internal.h b/net/mpls/internal.h
index 0df01a5395ee..80cb5bbcd946 100644
--- a/net/mpls/internal.h
+++ b/net/mpls/internal.h
@@ -185,6 +185,11 @@ static inline struct mpls_entry_decoded mpls_entry_decode(struct mpls_shim_hdr *
return result;
}
+#define mpls_dereference(net, p) \
+ rcu_dereference_protected( \
+ (p), \
+ lockdep_is_held(&(net)->mpls.platform_mutex))
+
static inline struct mpls_dev *mpls_dev_rcu(const struct net_device *dev)
{
return rcu_dereference(dev->mpls_ptr);
@@ -193,7 +198,7 @@ static inline struct mpls_dev *mpls_dev_rcu(const struct net_device *dev)
static inline struct mpls_dev *mpls_dev_get(const struct net *net,
const struct net_device *dev)
{
- return rcu_dereference_rtnl(dev->mpls_ptr);
+ return mpls_dereference(net, dev->mpls_ptr);
}
int nla_put_labels(struct sk_buff *skb, int attrtype, u8 labels,
--
2.51.1.838.g19442a804e-goog
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