Commit 5151a35c authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

Merge branch 'mptcp-misc-fixes-involving-fallback-to-tcp' 

Matthieu Baerts says:

====================
mptcp: misc. fixes involving fallback to TCP

- Patch 1: better handle DSS corruptions from a bugged peer: reducing
  warnings, doing a fallback or a reset depending on the subflow state.
  For >= v5.7.

- Patch 2: fix DSS corruption due to large pmtu xmit, where MPTCP was
  not taken into account. For >= v5.6.

- Patch 3: fallback when MPTCP opts are dropped after the first data
  packet, instead of resetting the connection. For >= v5.6.

- Patch 4: restrict the removal of a subflow to other closing states, a
  better fix, for a recent one. For >= v5.10.
====================

Link: https://patch.msgid.link/20241008-net-mptcp-fallback-fixes-v1-0-c6fb8e93e551@kernel.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parents d94785bb db0a37b7

net/ipv4/tcp_output.c

+1 −4
Original line number Diff line number Diff line
@@ -2342,10 +2342,7 @@ static bool tcp_can_coalesce_send_queue_head(struct sock *sk, int len) 
		if (len <= skb->len)

			break;



		if (unlikely(TCP_SKB_CB(skb)->eor) ||

		    tcp_has_tx_tstamp(skb) ||

		    !skb_pure_zcopy_same(skb, next) ||

		    skb_frags_readable(skb) != skb_frags_readable(next))

		if (tcp_has_tx_tstamp(skb) || !tcp_skb_can_collapse(skb, next))

			return false;



		len -= skb->len;

net/mptcp/mib.c

+2 −0
Original line number Diff line number Diff line
@@ -32,6 +32,8 @@ static const struct snmp_mib mptcp_snmp_list[] = { 
	SNMP_MIB_ITEM("MPJoinSynTxBindErr", MPTCP_MIB_JOINSYNTXBINDERR),

	SNMP_MIB_ITEM("MPJoinSynTxConnectErr", MPTCP_MIB_JOINSYNTXCONNECTERR),

	SNMP_MIB_ITEM("DSSNotMatching", MPTCP_MIB_DSSNOMATCH),

	SNMP_MIB_ITEM("DSSCorruptionFallback", MPTCP_MIB_DSSCORRUPTIONFALLBACK),

	SNMP_MIB_ITEM("DSSCorruptionReset", MPTCP_MIB_DSSCORRUPTIONRESET),

	SNMP_MIB_ITEM("InfiniteMapTx", MPTCP_MIB_INFINITEMAPTX),

	SNMP_MIB_ITEM("InfiniteMapRx", MPTCP_MIB_INFINITEMAPRX),

	SNMP_MIB_ITEM("DSSNoMatchTCP", MPTCP_MIB_DSSTCPMISMATCH),

net/mptcp/mib.h

+2 −0
Original line number Diff line number Diff line
@@ -27,6 +27,8 @@ enum linux_mptcp_mib_field { 
	MPTCP_MIB_JOINSYNTXBINDERR,	/* Not able to bind() the address when sending a SYN + MP_JOIN */

	MPTCP_MIB_JOINSYNTXCONNECTERR,	/* Not able to connect() when sending a SYN + MP_JOIN */

	MPTCP_MIB_DSSNOMATCH,		/* Received a new mapping that did not match the previous one */

	MPTCP_MIB_DSSCORRUPTIONFALLBACK,/* DSS corruption detected, fallback */

	MPTCP_MIB_DSSCORRUPTIONRESET,	/* DSS corruption detected, MPJ subflow reset */

	MPTCP_MIB_INFINITEMAPTX,	/* Sent an infinite mapping */

	MPTCP_MIB_INFINITEMAPRX,	/* Received an infinite mapping */

	MPTCP_MIB_DSSTCPMISMATCH,	/* DSS-mapping did not map with TCP's sequence numbers */

net/mptcp/pm_netlink.c

+2 −1
Original line number Diff line number Diff line
@@ -860,7 +860,8 @@ static void mptcp_pm_nl_rm_addr_or_subflow(struct mptcp_sock *msk, 
			int how = RCV_SHUTDOWN | SEND_SHUTDOWN;

			u8 id = subflow_get_local_id(subflow);



			if (inet_sk_state_load(ssk) == TCP_CLOSE)

			if ((1 << inet_sk_state_load(ssk)) &

			    (TCPF_FIN_WAIT1 | TCPF_FIN_WAIT2 | TCPF_CLOSING | TCPF_CLOSE))

				continue;

			if (rm_type == MPTCP_MIB_RMADDR && remote_id != rm_id)

				continue;

net/mptcp/protocol.c

+21 −3
Original line number Diff line number Diff line
@@ -620,6 +620,18 @@ static bool mptcp_check_data_fin(struct sock *sk) 
	return ret;

}



static void mptcp_dss_corruption(struct mptcp_sock *msk, struct sock *ssk)

{

	if (READ_ONCE(msk->allow_infinite_fallback)) {

		MPTCP_INC_STATS(sock_net(ssk),

				MPTCP_MIB_DSSCORRUPTIONFALLBACK);

		mptcp_do_fallback(ssk);

	} else {

		MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSCORRUPTIONRESET);

		mptcp_subflow_reset(ssk);

	}

}



static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk,

					   struct sock *ssk,

					   unsigned int *bytes)
@@ -692,10 +704,16 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk, 
				moved += len;

			seq += len;



			if (WARN_ON_ONCE(map_remaining < len))

				break;

			if (unlikely(map_remaining < len)) {

				DEBUG_NET_WARN_ON_ONCE(1);

				mptcp_dss_corruption(msk, ssk);

			}

		} else {

			WARN_ON_ONCE(!fin);

			if (unlikely(!fin)) {

				DEBUG_NET_WARN_ON_ONCE(1);

				mptcp_dss_corruption(msk, ssk);

			}



			sk_eat_skb(ssk, skb);

			done = true;

		}