From: "Matthieu Baerts (NGI0)" matttbe@kernel.org

As mentioned in the 'Fixes' commit, the port flag is only supported by the 'signal' flag, and not by the 'subflow' one. Then if both the 'signal' and 'subflow' flags are set, the problem is the same: the feature cannot work with the 'subflow' flag.

Technically, if both the 'signal' and 'subflow' flags are set, it will be possible to create the listening socket, but not to establish a subflow using this source port. So better to explicitly deny it, not to create some confusions because the expected behaviour is not possible.

Fixes: 09f12c3ab7a5 ("mptcp: allow to use port and non-signal in set_flags") Cc: stable@vger.kernel.org Reviewed-by: Mat Martineau martineau@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Link: https://patch.msgid.link/20240731-upstream-net-20240731-mptcp-endp-subflow-s... Signed-off-by: Jakub Kicinski kuba@kernel.org --- net/mptcp/pm_netlink.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c index 37954a0b087d..c921d07e5940 100644 --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -1328,8 +1328,8 @@ int mptcp_pm_nl_add_addr_doit(struct sk_buff *skb, struct genl_info *info) if (ret < 0) return ret;

- if (addr.addr.port && !(addr.flags & MPTCP_PM_ADDR_FLAG_SIGNAL)) { - GENL_SET_ERR_MSG(info, "flags must have signal when using port"); + if (addr.addr.port && !address_use_port(&addr)) { + GENL_SET_ERR_MSG(info, "flags must have signal and not subflow when using port"); return -EINVAL; }