From: Paolo Abeni pabeni@redhat.com
commit 6bc1fe7dd748ba5e76e7917d110837cafe7b931c upstream.
Let the caller specify the to-be-created subflow family.
For a given MPTCP socket created with the AF_INET6 family, the current userspace PM can already ask the kernel to create subflows in v4 and v6. If "plain" IPv4 addresses are passed to the kernel, they are automatically mapped in v6 addresses "by accident". This can be problematic because the userspace will need to pass different addresses, now the v4-mapped-v6 addresses to destroy this new subflow.
On the other hand, if the MPTCP socket has been created with the AF_INET family, the command to create a subflow in v6 will be accepted but the result will not be the one as expected as new subflow will be created in IPv4 using part of the v6 addresses passed to the kernel: not creating the expected subflow then.
No functional change intended for the in-kernel PM where an explicit enforcement is currently in place. This arbitrary enforcement will be leveraged by other patches in a future version.
Fixes: 702c2f646d42 ("mptcp: netlink: allow userspace-driven subflow establishment") Cc: stable@vger.kernel.org Co-developed-by: Matthieu Baerts matthieu.baerts@tessares.net Signed-off-by: Matthieu Baerts matthieu.baerts@tessares.net Signed-off-by: Paolo Abeni pabeni@redhat.com Reviewed-by: Mat Martineau mathew.j.martineau@linux.intel.com Signed-off-by: Matthieu Baerts matthieu.baerts@tessares.net Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/mptcp/protocol.c | 2 +- net/mptcp/protocol.h | 3 ++- net/mptcp/subflow.c | 9 +++++---- 3 files changed, 8 insertions(+), 6 deletions(-)
--- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -107,7 +107,7 @@ static int __mptcp_socket_create(struct struct socket *ssock; int err;
- err = mptcp_subflow_create_socket(sk, &ssock); + err = mptcp_subflow_create_socket(sk, sk->sk_family, &ssock); if (err) return err;
--- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -626,7 +626,8 @@ bool mptcp_addresses_equal(const struct /* called with sk socket lock held */ int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc, const struct mptcp_addr_info *remote); -int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock); +int mptcp_subflow_create_socket(struct sock *sk, unsigned short family, + struct socket **new_sock); void mptcp_info2sockaddr(const struct mptcp_addr_info *info, struct sockaddr_storage *addr, unsigned short family); --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -1492,7 +1492,7 @@ int __mptcp_subflow_connect(struct sock if (!mptcp_is_fully_established(sk)) goto err_out;
- err = mptcp_subflow_create_socket(sk, &sf); + err = mptcp_subflow_create_socket(sk, loc->family, &sf); if (err) goto err_out;
@@ -1604,7 +1604,9 @@ static void mptcp_subflow_ops_undo_overr #endif ssk->sk_prot = &tcp_prot; } -int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock) + +int mptcp_subflow_create_socket(struct sock *sk, unsigned short family, + struct socket **new_sock) { struct mptcp_subflow_context *subflow; struct net *net = sock_net(sk); @@ -1617,8 +1619,7 @@ int mptcp_subflow_create_socket(struct s if (unlikely(!sk->sk_socket)) return -EINVAL;
- err = sock_create_kern(net, sk->sk_family, SOCK_STREAM, IPPROTO_TCP, - &sf); + err = sock_create_kern(net, family, SOCK_STREAM, IPPROTO_TCP, &sf); if (err) return err;