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mptcp: fix locking for in-kernel listener creation

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For consistency, in mptcp_pm_nl_create_listen_socket(), we need to
call the __mptcp_nmpc_socket() under the msk socket lock.

Note that as a side effect, mptcp_subflow_create_socket() needs a
'nested' lockdep annotation, as it will acquire the subflow (kernel)
socket lock under the in-kernel listener msk socket lock.

The current lack of locking is almost harmless, because the relevant
socket is not exposed to the user space, but in future we will add
more complexity to the mentioned helper, let's play safe.

Fixes: 1729cf186d ("mptcp: create the listening socket for new port")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Paolo Abeni 2023-02-07 14:04:15 +01:00 committed by David S. Miller
parent 21e4356968
commit ad2171009d
2 changed files with 7 additions and 5 deletions
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10
net/mptcp/pm_netlink.c
View file

@ -998,8 +998,8 @@ static int mptcp_pm_nl_create_listen_socket(struct sock *sk,
{
int addrlen = sizeof(struct sockaddr_in);
struct sockaddr_storage addr;
struct mptcp_sock *msk;
struct socket *ssock;
struct sock *newsk;
int backlog = 1024;
int err;
@ -1008,11 +1008,13 @@ static int mptcp_pm_nl_create_listen_socket(struct sock *sk,
if (err)
return err;
msk = mptcp_sk(entry->lsk->sk);
if (!msk)
newsk = entry->lsk->sk;
if (!newsk)
return -EINVAL;
ssock = __mptcp_nmpc_socket(msk);
lock_sock(newsk);
ssock = __mptcp_nmpc_socket(mptcp_sk(newsk));
release_sock(newsk);
if (!ssock)
return -EINVAL;

2
net/mptcp/subflow.c
View file

@ -1679,7 +1679,7 @@ int mptcp_subflow_create_socket(struct sock *sk, unsigned short family,
if (err)
return err;
lock_sock(sf->sk);
lock_sock_nested(sf->sk, SINGLE_DEPTH_NESTING);
/* the newly created socket has to be in the same cgroup as its parent */
mptcp_attach_cgroup(sk, sf->sk);