Commit e833eb25 authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by Jakub Kicinski
Browse files

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: default avatarKuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: default avatarGuillaume Nault <gnault@redhat.com>
Link: https://patch.msgid.link/20251029173344.2934622-13-kuniyu@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent fb2b77b9

include/net/netns/mpls.h

+1 −0
Original line number Diff line number Diff line
@@ -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;

};

net/mpls/af_mpls.c

+36 −19
Original line number Diff line number Diff line
@@ -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);

}

net/mpls/internal.h

+6 −1
Original line number Diff line number Diff line
@@ -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,