Commit 86e8921d authored by Eric Dumazet's avatar Eric Dumazet Committed by Paolo Abeni
Browse files

sock_diag: allow concurrent operation in sock_diag_rcv_msg() 



TCPDIAG_GETSOCK and DCCPDIAG_GETSOCK diag are serialized
on sock_diag_table_mutex.

This is to make sure inet_diag module is not unloaded
while diag was ongoing.

It is time to get rid of this mutex and use RCU protection,
allowing full parallelism.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarGuillaume Nault <gnault@redhat.com>
Reviewed-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 1d55a697

include/linux/sock_diag.h

+7 −2
Original line number Diff line number Diff line
@@ -23,8 +23,13 @@ struct sock_diag_handler { 
int sock_diag_register(const struct sock_diag_handler *h);

void sock_diag_unregister(const struct sock_diag_handler *h);



void sock_diag_register_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh));

void sock_diag_unregister_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh));

struct sock_diag_inet_compat {

	struct module *owner;

	int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh);

};



void sock_diag_register_inet_compat(const struct sock_diag_inet_compat *ptr);

void sock_diag_unregister_inet_compat(const struct sock_diag_inet_compat *ptr);



u64 __sock_gen_cookie(struct sock *sk);

net/core/sock_diag.c

+26 −17
Original line number Diff line number Diff line
@@ -17,8 +17,9 @@ 
#include <linux/sock_diag.h>



static const struct sock_diag_handler __rcu *sock_diag_handlers[AF_MAX];

static int (*inet_rcv_compat)(struct sk_buff *skb, struct nlmsghdr *nlh);

static DEFINE_MUTEX(sock_diag_table_mutex);



static struct sock_diag_inet_compat __rcu *inet_rcv_compat;



static struct workqueue_struct *broadcast_wq;



DEFINE_COOKIE(sock_cookie);
@@ -184,19 +185,20 @@ void sock_diag_broadcast_destroy(struct sock *sk) 
	queue_work(broadcast_wq, &bsk->work);

}



void sock_diag_register_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh))

void sock_diag_register_inet_compat(const struct sock_diag_inet_compat *ptr)

{

	mutex_lock(&sock_diag_table_mutex);

	inet_rcv_compat = fn;

	mutex_unlock(&sock_diag_table_mutex);

	xchg((__force const struct sock_diag_inet_compat **)&inet_rcv_compat,

	     ptr);

}

EXPORT_SYMBOL_GPL(sock_diag_register_inet_compat);



void sock_diag_unregister_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh))

void sock_diag_unregister_inet_compat(const struct sock_diag_inet_compat *ptr)

{

	mutex_lock(&sock_diag_table_mutex);

	inet_rcv_compat = NULL;

	mutex_unlock(&sock_diag_table_mutex);

	const struct sock_diag_inet_compat *old;



	old = xchg((__force const struct sock_diag_inet_compat **)&inet_rcv_compat,

		   NULL);

	WARN_ON_ONCE(old != ptr);

}

EXPORT_SYMBOL_GPL(sock_diag_unregister_inet_compat);
@@ -259,20 +261,27 @@ static int __sock_diag_cmd(struct sk_buff *skb, struct nlmsghdr *nlh) 
static int sock_diag_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,

			     struct netlink_ext_ack *extack)

{

	const struct sock_diag_inet_compat *ptr;

	int ret;



	switch (nlh->nlmsg_type) {

	case TCPDIAG_GETSOCK:

	case DCCPDIAG_GETSOCK:

		if (inet_rcv_compat == NULL)



		if (!rcu_access_pointer(inet_rcv_compat))

			sock_load_diag_module(AF_INET, 0);



		mutex_lock(&sock_diag_table_mutex);

		if (inet_rcv_compat != NULL)

			ret = inet_rcv_compat(skb, nlh);

		else

		rcu_read_lock();

		ptr = rcu_dereference(inet_rcv_compat);

		if (ptr && !try_module_get(ptr->owner))

			ptr = NULL;

		rcu_read_unlock();



		ret = -EOPNOTSUPP;

		mutex_unlock(&sock_diag_table_mutex);

		if (ptr) {

			ret = ptr->fn(skb, nlh);

			module_put(ptr->owner);

		}



		return ret;

	case SOCK_DIAG_BY_FAMILY:

net/ipv4/inet_diag.c

+7 −2
Original line number Diff line number Diff line
@@ -1527,6 +1527,11 @@ void inet_diag_unregister(const struct inet_diag_handler *h) 
}

EXPORT_SYMBOL_GPL(inet_diag_unregister);



static const struct sock_diag_inet_compat inet_diag_compat = {

	.owner	= THIS_MODULE,

	.fn	= inet_diag_rcv_msg_compat,

};



static int __init inet_diag_init(void)

{

	const int inet_diag_table_size = (IPPROTO_MAX *
@@ -1545,7 +1550,7 @@ static int __init inet_diag_init(void) 
	if (err)

		goto out_free_inet;



	sock_diag_register_inet_compat(inet_diag_rcv_msg_compat);

	sock_diag_register_inet_compat(&inet_diag_compat);

out:

	return err;
@@ -1560,7 +1565,7 @@ static void __exit inet_diag_exit(void) 
{

	sock_diag_unregister(&inet6_diag_handler);

	sock_diag_unregister(&inet_diag_handler);

	sock_diag_unregister_inet_compat(inet_diag_rcv_msg_compat);

	sock_diag_unregister_inet_compat(&inet_diag_compat);

	kfree(inet_diag_table);

}