mptcp: fix locking for in-kernel listener creation

[ Upstream commit ad2171009d968104ccda9dc517f5a3ba891515db ]

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: 1729cf186d8a ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index fdf2ee29f76238754d56a08f4b162af5613554fc..5e38a0abbabae76c76752db9421f7a54fd32e90a 100644 (file)
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -992,8 +992,8 @@ 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;
 
@@ -1002,11 +1002,13 @@ 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;
 

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 929b0ee8b3d5f6830fbb72e84fbcf2ce3d718f30..c4971bc42f60f33b91611f81746c4e8745986dc1 100644 (file)
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1631,7 +1631,7 @@ 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);