From 1423c12b4f0c6a10830407a99e90a68c278205cc Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Thu, 12 Jan 2023 18:42:51 +0100 Subject: [PATCH] mptcp: explicitly specify sock family at subflow creation time 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 Signed-off-by: Matthieu Baerts Signed-off-by: Paolo Abeni Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/mptcp/protocol.c | 2 +- net/mptcp/protocol.h | 3 ++- net/mptcp/subflow.c | 9 +++++---- 3 files changed, 8 insertions(+), 6 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index e97465f..29849d7 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -107,7 +107,7 @@ static int __mptcp_socket_create(struct mptcp_sock *msk) 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; diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 62e9ff2..1097428 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -626,7 +626,8 @@ bool mptcp_addresses_equal(const struct mptcp_addr_info *a, /* 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); diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 9d3701f..5220435 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -1492,7 +1492,7 @@ int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc, 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_override(struct sock *ssk) #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 sock *sk, struct socket **new_sock) 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; -- 2.7.4