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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: Eric Dumazet <edumazet@google.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Eric Dumazet 2024-01-22 11:26:01 +00:00 committed by Paolo Abeni
parent 1d55a69747
commit 86e8921df0
3 changed files with 40 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
include/linux/sock_diag.h
View File

@ -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);

43
net/core/sock_diag.c
View File

@ -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
ret = -EOPNOTSUPP;
mutex_unlock(&sock_diag_table_mutex);
rcu_read_lock();
ptr = rcu_dereference(inet_rcv_compat);
if (ptr && !try_module_get(ptr->owner))
ptr = NULL;
rcu_read_unlock();
ret = -EOPNOTSUPP;
if (ptr) {
ret = ptr->fn(skb, nlh);
module_put(ptr->owner);
}
return ret;
case SOCK_DIAG_BY_FAMILY:

9
net/ipv4/inet_diag.c
View File

@ -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);
}