[PATCH 5.9 007/757] mptcp: subflows garbage collection

Greg Kroah-Hartman
2020-10-27T15:58:51Z

From: Paolo Abeni <pabeni@redhat.com>

[ Upstream commit 0e4f35d7880157ceccf0a58377d778b02762af82 ]

The msk can close MP_JOIN subflows if the initial handshake
fails. Currently such subflows are kept alive in the
conn_list until the msk itself is closed.

Beyond the wasted memory, we could end-up sending the
DATA_FIN and the DATA_FIN ack on such socket, even after a
reset.

Fixes: 43b54c6ee382 ("mptcp: Use full MPTCP-level disconnect state machine")
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/mptcp/protocol.c | 17 +++++++++++++++++
net/mptcp/protocol.h | 1 +
net/mptcp/subflow.c | 6 ++++++
3 files changed, 24 insertions(+)

--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1383,6 +1383,20 @@ static void pm_work(struct mptcp_sock *m
spin_unlock_bh(&msk->pm.lock);
}

+static void __mptcp_close_subflow(struct mptcp_sock *msk)
+{
+ struct mptcp_subflow_context *subflow, *tmp;
+
+ list_for_each_entry_safe(subflow, tmp, &msk->conn_list, node) {
+ struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+
+ if (inet_sk_state_load(ssk) != TCP_CLOSE)
+ continue;
+
+ __mptcp_close_ssk((struct sock *)msk, ssk, subflow, 0);
+ }
+}
+
static void mptcp_worker(struct work_struct *work)
{
struct mptcp_sock *msk = container_of(work, struct mptcp_sock, work);
@@ -1400,6 +1414,9 @@ static void mptcp_worker(struct work_str
mptcp_clean_una(sk);
mptcp_check_data_fin_ack(sk);
__mptcp_flush_join_list(msk);
+ if (test_and_clear_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))
+ __mptcp_close_subflow(msk);
+
__mptcp_move_skbs(msk);

if (msk->pm.status)
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -90,6 +90,7 @@
#define MPTCP_WORK_RTX 2
#define MPTCP_WORK_EOF 3
#define MPTCP_FALLBACK_DONE 4
+#define MPTCP_WORK_CLOSE_SUBFLOW 5

struct mptcp_options_received {
u64 sndr_key;
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -272,9 +272,15 @@ static bool subflow_thmac_valid(struct m

void mptcp_subflow_reset(struct sock *ssk)
{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
+ struct sock *sk = subflow->conn;
+
tcp_set_state(ssk, TCP_CLOSE);
tcp_send_active_reset(ssk, GFP_ATOMIC);
tcp_done(ssk);
+ if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags) &&
+ schedule_work(&mptcp_sk(sk)->work))
+ sock_hold(sk);
}

static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)