mptcp: MP_FAIL suboption receiving

This patch added handling for receiving MP_FAIL suboption.

Add a new members mp_fail and fail_seq in struct mptcp_options_received.
When MP_FAIL suboption is received, set mp_fail to 1 and save the sequence
number to fail_seq.

Then invoke mptcp_pm_mp_fail_received to deal with the MP_FAIL suboption.
Signed-off-by: Geliang Tang <geliangtang@xiaomi.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/mptcp/options.c

@@ -336,6 +336,16 @@ static void mptcp_parse_option(const struct sk_buff *skb,
 		mp_opt->reset_reason = *ptr;
 		break;
 
+	case MPTCPOPT_MP_FAIL:
+		if (opsize != TCPOLEN_MPTCP_FAIL)
+			break;
+
+		ptr += 2;
+		mp_opt->mp_fail = 1;
+		mp_opt->fail_seq = get_unaligned_be64(ptr);
+		pr_debug("MP_FAIL: data_seq=%llu", mp_opt->fail_seq);
+		break;
+
 	default:
 		break;
 	}
@@ -364,6 +374,7 @@ void mptcp_get_options(const struct sock *sk,
 	mp_opt->reset = 0;
 	mp_opt->csum_reqd = READ_ONCE(msk->csum_enabled);
 	mp_opt->deny_join_id0 = 0;
+	mp_opt->mp_fail = 0;
 
 	length = (th->doff * 4) - sizeof(struct tcphdr);
 	ptr = (const unsigned char *)(th + 1);
@@ -1145,6 +1156,11 @@ bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
 		mp_opt.mp_prio = 0;
 	}
 
+	if (mp_opt.mp_fail) {
+		mptcp_pm_mp_fail_received(sk, mp_opt.fail_seq);
+		mp_opt.mp_fail = 0;
+	}
+
 	if (mp_opt.reset) {
 		subflow->reset_seen = 1;
 		subflow->reset_reason = mp_opt.reset_reason;

net/mptcp/pm.c

@@ -249,6 +249,11 @@ void mptcp_pm_mp_prio_received(struct sock *sk, u8 bkup)
 	mptcp_event(MPTCP_EVENT_SUB_PRIORITY, mptcp_sk(subflow->conn), sk, GFP_ATOMIC);
 }
 
+void mptcp_pm_mp_fail_received(struct sock *sk, u64 fail_seq)
+{
+	pr_debug("fail_seq=%llu", fail_seq);
+}
+
 /* path manager helpers */
 
 bool mptcp_pm_add_addr_signal(struct mptcp_sock *msk, struct sk_buff *skb,

net/mptcp/protocol.h

@@ -140,6 +140,7 @@ struct mptcp_options_received {
 		add_addr : 1,
 		rm_addr : 1,
 		mp_prio : 1,
+		mp_fail : 1,
 		echo : 1,
 		csum_reqd : 1,
 		backup : 1,
@@ -161,6 +162,7 @@ struct mptcp_options_received {
 	u64	ahmac;
 	u8	reset_reason:4;
 	u8	reset_transient:1;
+	u64	fail_seq;
 };
 
 static inline __be32 mptcp_option(u8 subopt, u8 len, u8 nib, u8 field)
@@ -726,6 +728,7 @@ void mptcp_pm_mp_prio_received(struct sock *sk, u8 bkup);
 int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk,
 				 struct mptcp_addr_info *addr,
 				 u8 bkup);
+void mptcp_pm_mp_fail_received(struct sock *sk, u64 fail_seq);
 void mptcp_pm_free_anno_list(struct mptcp_sock *msk);
 bool mptcp_pm_sport_in_anno_list(struct mptcp_sock *msk, const struct sock *sk);
 struct mptcp_pm_add_entry *