MPTCP creates subflows for data transmission, and these sockets should not
be added to sockmap because MPTCP sets specialized data_ready handlers
that would be overridden by sockmap.
Additionally, for the parent socket of MPTCP subflows (plain TCP socket),
MPTCP sk requires specific protocol handling that conflicts with sockmap's
operation(mptcp_prot).
This patch adds proper checks to reject MPTCP subflows and their parent
sockets from being added to sockmap, while preserving compatibility with
reuseport functionality for listening MPTCP sockets.
Fixes: 0b4f33def7bb ("mptcp: fix tcp fallback crash")
Signed-off-by: Jiayuan Chen <[email protected]>
---
net/core/sock_map.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index 5947b38e4f8b..da21deb970b3 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -535,6 +535,15 @@ static bool sock_map_redirect_allowed(const struct sock
*sk)
static bool sock_map_sk_is_suitable(const struct sock *sk)
{
+ if ((sk_is_tcp(sk) && sk_is_mptcp(sk)) /* subflow */ ||
+ (sk->sk_protocol == IPPROTO_MPTCP && sk->sk_state != TCP_LISTEN)) {
+ /* Disallow MPTCP subflows and their parent socket.
+ * However, a TCP_LISTEN MPTCP socket is permitted because
+ * sockmap can also serve for reuseport socket selection.
+ */
+ pr_err_once("sockmap: MPTCP sockets are not supported\n");
+ return false;
+ }
return !!sk->sk_prot->psock_update_sk_prot;
}
--
2.43.0
