From 4cf8b7e48a09745145881b311fe6a9154ba69ebc Mon Sep 17 00:00:00 2001
From: Paolo Abeni <pabeni@redhat.com>
Date: Thu, 23 Jul 2020 13:02:36 +0200
Subject: [PATCH] subflow: introduce and use mptcp_can_accept_new_subflow()
So that we can easily perform some basic PM-related
adimission checks before creating the child socket.
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Tested-by: Christoph Paasch <cpaasch@apple.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/mptcp/subflow.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index ada04df6f99f5..e645483d1200d 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -53,6 +53,12 @@ static void subflow_generate_hmac(u64 key1, u64 key2, u32 nonce1, u32 nonce2,
mptcp_crypto_hmac_sha(key1, key2, msg, 8, hmac);
}
+static bool mptcp_can_accept_new_subflow(const struct mptcp_sock *msk)
+{
+ return mptcp_is_fully_established((void *)msk) &&
+ READ_ONCE(msk->pm.accept_subflow);
+}
+
/* validate received token and create truncated hmac and nonce for SYN-ACK */
static struct mptcp_sock *subflow_token_join_request(struct request_sock *req,
const struct sk_buff *skb)
@@ -443,6 +449,7 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
} else if (subflow_req->mp_join) {
mptcp_get_options(skb, &mp_opt);
if (!mp_opt.mp_join ||
+ !mptcp_can_accept_new_subflow(subflow_req->msk) ||
!subflow_hmac_valid(req, &mp_opt)) {
SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC);
fallback = true;
--
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