[PATCH net-next 0/8] mptcp: TCP fallback for established connections

[PATCH net-next 0/8] mptcp: TCP fallback for established connections

[Mat Martineau]

RFC 8684 allows some MPTCP connections to fall back to regular TCP when
the MPTCP DSS checksum detects middlebox interference, there is only a
single subflow, and there is no unacknowledged out-of-sequence
data. When this condition is detected, the stack sends a MPTCP DSS
option with an "infinite mapping" to signal that a fallback is
happening, and the peers will stop sending MPTCP options in their TCP
headers. The Linux MPTCP stack has not yet supported this type of
fallback, instead closing the connection when the MPTCP checksum fails.

This series adds support for fallback to regular TCP in a more limited
scenario, for only MPTCP connections that have never connected
additional subflows or transmitted out-of-sequence data. The selftests
are also updated to check new MIBs that track infinite mappings.


Geliang Tang (8):
  mptcp: don't send RST for single subflow
  mptcp: add the fallback check
  mptcp: track and update contiguous data status
  mptcp: infinite mapping sending
  mptcp: infinite mapping receiving
  mptcp: add mib for infinite map sending
  mptcp: dump infinite_map field in mptcp_dump_mpext
  selftests: mptcp: add infinite map mibs check

 include/net/mptcp.h                           |  3 +-
 include/trace/events/mptcp.h                  |  6 +-
 net/mptcp/mib.c                               |  1 +
 net/mptcp/mib.h                               |  1 +
 net/mptcp/options.c                           |  8 ++-
 net/mptcp/pm.c                                |  6 ++
 net/mptcp/protocol.c                          | 21 +++++++
 net/mptcp/protocol.h                          | 13 +++++
 net/mptcp/subflow.c                           | 57 +++++++++++--------
 .../testing/selftests/net/mptcp/mptcp_join.sh | 36 +++++++++++-
 10 files changed, 121 insertions(+), 31 deletions(-)


base-commit: c78c5a660439d4d341a03b651541fda3ebe76160
-- 
2.36.0

[PATCH net-next 1/8] mptcp: don't send RST for single subflow

[Mat Martineau]

From: Geliang Tang <geliang.tang@suse.com>

When a bad checksum is detected and a single subflow is in use, don't
send RST + MP_FAIL, send data_ack + MP_FAIL instead.

So invoke tcp_send_active_reset() only when mptcp_has_another_subflow()
is true.

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 net/mptcp/subflow.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index aba260f547da..f217926f6a9c 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1206,14 +1206,14 @@ static bool subflow_check_data_avail(struct sock *ssk)
 	/* RFC 8684 section 3.7. */
 	if (subflow->send_mp_fail) {
 		if (mptcp_has_another_subflow(ssk)) {
+			ssk->sk_err = EBADMSG;
+			tcp_set_state(ssk, TCP_CLOSE);
+			subflow->reset_transient = 0;
+			subflow->reset_reason = MPTCP_RST_EMIDDLEBOX;
+			tcp_send_active_reset(ssk, GFP_ATOMIC);
 			while ((skb = skb_peek(&ssk->sk_receive_queue)))
 				sk_eat_skb(ssk, skb);
 		}
-		ssk->sk_err = EBADMSG;
-		tcp_set_state(ssk, TCP_CLOSE);
-		subflow->reset_transient = 0;
-		subflow->reset_reason = MPTCP_RST_EMIDDLEBOX;
-		tcp_send_active_reset(ssk, GFP_ATOMIC);
 		WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA);
 		return true;
 	}
-- 
2.36.0

[PATCH net-next 2/8] mptcp: add the fallback check

[Mat Martineau]

From: Geliang Tang <geliang.tang@suse.com>

This patch adds the fallback check in subflow_check_data_avail(). Only
do the fallback when the msk hasn't fallen back yet.

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 net/mptcp/subflow.c | 45 ++++++++++++++++++++++++---------------------
 1 file changed, 24 insertions(+), 21 deletions(-)

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index f217926f6a9c..7f26a5b04ad3 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1203,35 +1203,38 @@ static bool subflow_check_data_avail(struct sock *ssk)
 	return false;
 
 fallback:
-	/* RFC 8684 section 3.7. */
-	if (subflow->send_mp_fail) {
-		if (mptcp_has_another_subflow(ssk)) {
+	if (!__mptcp_check_fallback(msk)) {
+		/* RFC 8684 section 3.7. */
+		if (subflow->send_mp_fail) {
+			if (mptcp_has_another_subflow(ssk)) {
+				ssk->sk_err = EBADMSG;
+				tcp_set_state(ssk, TCP_CLOSE);
+				subflow->reset_transient = 0;
+				subflow->reset_reason = MPTCP_RST_EMIDDLEBOX;
+				tcp_send_active_reset(ssk, GFP_ATOMIC);
+				while ((skb = skb_peek(&ssk->sk_receive_queue)))
+					sk_eat_skb(ssk, skb);
+			}
+			WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA);
+			return true;
+		}
+
+		if (subflow->mp_join || subflow->fully_established) {
+			/* fatal protocol error, close the socket.
+			 * subflow_error_report() will introduce the appropriate barriers
+			 */
 			ssk->sk_err = EBADMSG;
 			tcp_set_state(ssk, TCP_CLOSE);
 			subflow->reset_transient = 0;
-			subflow->reset_reason = MPTCP_RST_EMIDDLEBOX;
+			subflow->reset_reason = MPTCP_RST_EMPTCP;
 			tcp_send_active_reset(ssk, GFP_ATOMIC);
-			while ((skb = skb_peek(&ssk->sk_receive_queue)))
-				sk_eat_skb(ssk, skb);
+			WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA);
+			return false;
 		}
-		WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA);
-		return true;
-	}
 
-	if (subflow->mp_join || subflow->fully_established) {
-		/* fatal protocol error, close the socket.
-		 * subflow_error_report() will introduce the appropriate barriers
-		 */
-		ssk->sk_err = EBADMSG;
-		tcp_set_state(ssk, TCP_CLOSE);
-		subflow->reset_transient = 0;
-		subflow->reset_reason = MPTCP_RST_EMPTCP;
-		tcp_send_active_reset(ssk, GFP_ATOMIC);
-		WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA);
-		return false;
+		__mptcp_do_fallback(msk);
 	}
 
-	__mptcp_do_fallback(msk);
 	skb = skb_peek(&ssk->sk_receive_queue);
 	subflow->map_valid = 1;
 	subflow->map_seq = READ_ONCE(msk->ack_seq);
-- 
2.36.0

[PATCH net-next 3/8] mptcp: track and update contiguous data status

[Mat Martineau]

From: Geliang Tang <geliang.tang@suse.com>

This patch adds a new member allow_infinite_fallback in mptcp_sock,
which is initialized to 'true' when the connection begins and is set
to 'false' on any retransmit or successful MP_JOIN. Only do infinite
mapping fallback if there is a single subflow AND there have been no
retransmissions AND there have never been any MP_JOINs.

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 net/mptcp/protocol.c | 3 +++
 net/mptcp/protocol.h | 1 +
 net/mptcp/subflow.c  | 4 +++-
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 0492aa9308c7..6d653914e9fe 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2465,6 +2465,7 @@ static void __mptcp_retrans(struct sock *sk)
 		dfrag->already_sent = max(dfrag->already_sent, info.sent);
 		tcp_push(ssk, 0, info.mss_now, tcp_sk(ssk)->nonagle,
 			 info.size_goal);
+		WRITE_ONCE(msk->allow_infinite_fallback, false);
 	}
 
 	release_sock(ssk);
@@ -2539,6 +2540,7 @@ static int __mptcp_init_sock(struct sock *sk)
 	msk->first = NULL;
 	inet_csk(sk)->icsk_sync_mss = mptcp_sync_mss;
 	WRITE_ONCE(msk->csum_enabled, mptcp_is_checksum_enabled(sock_net(sk)));
+	WRITE_ONCE(msk->allow_infinite_fallback, true);
 	msk->recovery = false;
 
 	mptcp_pm_data_init(msk);
@@ -3275,6 +3277,7 @@ bool mptcp_finish_join(struct sock *ssk)
 	}
 
 	subflow->map_seq = READ_ONCE(msk->ack_seq);
+	WRITE_ONCE(msk->allow_infinite_fallback, false);
 
 out:
 	mptcp_event(MPTCP_EVENT_SUB_ESTABLISHED, msk, ssk, GFP_ATOMIC);
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index aca1fb56523f..88d292374599 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -263,6 +263,7 @@ struct mptcp_sock {
 	bool		rcv_fastclose;
 	bool		use_64bit_ack; /* Set when we received a 64-bit DSN */
 	bool		csum_enabled;
+	bool		allow_infinite_fallback;
 	u8		recvmsg_inq:1,
 			cork:1,
 			nodelay:1;
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 7f26a5b04ad3..31dcb550316f 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1206,7 +1206,8 @@ static bool subflow_check_data_avail(struct sock *ssk)
 	if (!__mptcp_check_fallback(msk)) {
 		/* RFC 8684 section 3.7. */
 		if (subflow->send_mp_fail) {
-			if (mptcp_has_another_subflow(ssk)) {
+			if (mptcp_has_another_subflow(ssk) ||
+			    !READ_ONCE(msk->allow_infinite_fallback)) {
 				ssk->sk_err = EBADMSG;
 				tcp_set_state(ssk, TCP_CLOSE);
 				subflow->reset_transient = 0;
@@ -1486,6 +1487,7 @@ int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
 	/* discard the subflow socket */
 	mptcp_sock_graft(ssk, sk->sk_socket);
 	iput(SOCK_INODE(sf));
+	WRITE_ONCE(msk->allow_infinite_fallback, false);
 	return err;
 
 failed_unlink:
-- 
2.36.0

[PATCH net-next 4/8] mptcp: infinite mapping sending

[Mat Martineau]

From: Geliang Tang <geliang.tang@suse.com>

This patch adds the infinite mapping sending logic.

Add a new flag send_infinite_map in struct mptcp_subflow_context. Set
it true when a single contiguous subflow is in use and the
allow_infinite_fallback flag is true in mptcp_pm_mp_fail_received().

In mptcp_sendmsg_frag(), if this flag is true, call the new function
mptcp_update_infinite_map() to set the infinite mapping.

Add a new flag infinite_map in struct mptcp_ext, set it true in
mptcp_update_infinite_map(), and check this flag in a new helper
mptcp_check_infinite_map().

In mptcp_update_infinite_map(), set data_len to 0, and clear the
send_infinite_map flag, then do fallback.

In mptcp_established_options(), use the helper mptcp_check_infinite_map()
to let the infinite mapping DSS can be sent out in the fallback mode.

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 include/net/mptcp.h  |  3 ++-
 net/mptcp/options.c  |  8 ++++++--
 net/mptcp/pm.c       |  6 ++++++
 net/mptcp/protocol.c | 17 +++++++++++++++++
 net/mptcp/protocol.h | 12 ++++++++++++
 5 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 0a3b0fb04a3b..8b1afd6f5cc4 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -35,7 +35,8 @@ struct mptcp_ext {
 			frozen:1,
 			reset_transient:1;
 	u8		reset_reason:4,
-			csum_reqd:1;
+			csum_reqd:1,
+			infinite_map:1;
 };
 
 #define MPTCP_RM_IDS_MAX	8
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 325383646f5c..88f4ebbd6515 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -825,7 +825,7 @@ bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
 
 	opts->suboptions = 0;
 
-	if (unlikely(__mptcp_check_fallback(msk)))
+	if (unlikely(__mptcp_check_fallback(msk) && !mptcp_check_infinite_map(skb)))
 		return false;
 
 	if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) {
@@ -1340,8 +1340,12 @@ void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
 			put_unaligned_be32(mpext->subflow_seq, ptr);
 			ptr += 1;
 			if (opts->csum_reqd) {
+				/* data_len == 0 is reserved for the infinite mapping,
+				 * the checksum will also be set to 0.
+				 */
 				put_unaligned_be32(mpext->data_len << 16 |
-						   mptcp_make_csum(mpext), ptr);
+						   (mpext->data_len ? mptcp_make_csum(mpext) : 0),
+						   ptr);
 			} else {
 				put_unaligned_be32(mpext->data_len << 16 |
 						   TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 8aa0cdb7ad46..5c36870d3420 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -285,7 +285,13 @@ void mptcp_pm_mp_prio_received(struct sock *ssk, u8 bkup)
 
 void mptcp_pm_mp_fail_received(struct sock *sk, u64 fail_seq)
 {
+	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
+
 	pr_debug("fail_seq=%llu", fail_seq);
+
+	if (!mptcp_has_another_subflow(sk) && READ_ONCE(msk->allow_infinite_fallback))
+		subflow->send_infinite_map = 1;
 }
 
 /* path manager helpers */
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 6d653914e9fe..161c07f49db6 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1229,6 +1229,21 @@ static void mptcp_update_data_checksum(struct sk_buff *skb, int added)
 	mpext->csum = csum_fold(csum_block_add(csum, skb_checksum(skb, offset, added, 0), offset));
 }
 
+static void mptcp_update_infinite_map(struct mptcp_sock *msk,
+				      struct sock *ssk,
+				      struct mptcp_ext *mpext)
+{
+	if (!mpext)
+		return;
+
+	mpext->infinite_map = 1;
+	mpext->data_len = 0;
+
+	mptcp_subflow_ctx(ssk)->send_infinite_map = 0;
+	pr_fallback(msk);
+	__mptcp_do_fallback(msk);
+}
+
 static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
 			      struct mptcp_data_frag *dfrag,
 			      struct mptcp_sendmsg_info *info)
@@ -1360,6 +1375,8 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
 out:
 	if (READ_ONCE(msk->csum_enabled))
 		mptcp_update_data_checksum(skb, copy);
+	if (mptcp_subflow_ctx(ssk)->send_infinite_map)
+		mptcp_update_infinite_map(msk, ssk, mpext);
 	trace_mptcp_sendmsg_frag(mpext);
 	mptcp_subflow_ctx(ssk)->rel_write_seq += copy;
 	return copy;
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 88d292374599..61d600693ffd 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -441,6 +441,7 @@ struct mptcp_subflow_context {
 		send_mp_prio : 1,
 		send_mp_fail : 1,
 		send_fastclose : 1,
+		send_infinite_map : 1,
 		rx_eof : 1,
 		can_ack : 1,        /* only after processing the remote a key */
 		disposable : 1,	    /* ctx can be free at ulp release time */
@@ -877,6 +878,17 @@ static inline void mptcp_do_fallback(struct sock *sk)
 
 #define pr_fallback(a) pr_debug("%s:fallback to TCP (msk=%p)", __func__, a)
 
+static inline bool mptcp_check_infinite_map(struct sk_buff *skb)
+{
+	struct mptcp_ext *mpext;
+
+	mpext = skb ? mptcp_get_ext(skb) : NULL;
+	if (mpext && mpext->infinite_map)
+		return true;
+
+	return false;
+}
+
 static inline bool subflow_simultaneous_connect(struct sock *sk)
 {
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
-- 
2.36.0

[PATCH net-next 5/8] mptcp: infinite mapping receiving

[Mat Martineau]

From: Geliang Tang <geliang.tang@suse.com>

This patch adds the infinite mapping receiving logic. When the infinite
mapping is received, set the map_data_len of the subflow to 0.

In subflow_check_data_avail(), only reset the subflow when the map_data_len
of the subflow is non-zero.

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 net/mptcp/subflow.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 31dcb550316f..30ffb00661bb 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1006,7 +1006,9 @@ static enum mapping_status get_mapping_status(struct sock *ssk,
 
 	data_len = mpext->data_len;
 	if (data_len == 0) {
+		pr_debug("infinite mapping received");
 		MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX);
+		subflow->map_data_len = 0;
 		return MAPPING_INVALID;
 	}
 
@@ -1220,7 +1222,7 @@ static bool subflow_check_data_avail(struct sock *ssk)
 			return true;
 		}
 
-		if (subflow->mp_join || subflow->fully_established) {
+		if ((subflow->mp_join || subflow->fully_established) && subflow->map_data_len) {
 			/* fatal protocol error, close the socket.
 			 * subflow_error_report() will introduce the appropriate barriers
 			 */
-- 
2.36.0

[PATCH net-next 6/8] mptcp: add mib for infinite map sending

[Mat Martineau]

From: Geliang Tang <geliang.tang@suse.com>

This patch adds a new mib named MPTCP_MIB_INFINITEMAPTX, increase it
when a infinite mapping has been sent out.

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 net/mptcp/mib.c      | 1 +
 net/mptcp/mib.h      | 1 +
 net/mptcp/protocol.c | 1 +
 3 files changed, 3 insertions(+)

diff --git a/net/mptcp/mib.c b/net/mptcp/mib.c
index e55d3dfbee0c..d93a8c9996fd 100644
--- a/net/mptcp/mib.c
+++ b/net/mptcp/mib.c
@@ -24,6 +24,7 @@ static const struct snmp_mib mptcp_snmp_list[] = {
 	SNMP_MIB_ITEM("MPJoinAckRx", MPTCP_MIB_JOINACKRX),
 	SNMP_MIB_ITEM("MPJoinAckHMacFailure", MPTCP_MIB_JOINACKMAC),
 	SNMP_MIB_ITEM("DSSNotMatching", MPTCP_MIB_DSSNOMATCH),
+	SNMP_MIB_ITEM("InfiniteMapTx", MPTCP_MIB_INFINITEMAPTX),
 	SNMP_MIB_ITEM("InfiniteMapRx", MPTCP_MIB_INFINITEMAPRX),
 	SNMP_MIB_ITEM("DSSNoMatchTCP", MPTCP_MIB_DSSTCPMISMATCH),
 	SNMP_MIB_ITEM("DataCsumErr", MPTCP_MIB_DATACSUMERR),
diff --git a/net/mptcp/mib.h b/net/mptcp/mib.h
index 00576179a619..529d07af9e14 100644
--- a/net/mptcp/mib.h
+++ b/net/mptcp/mib.h
@@ -17,6 +17,7 @@ enum linux_mptcp_mib_field {
 	MPTCP_MIB_JOINACKRX,		/* Received an ACK + MP_JOIN */
 	MPTCP_MIB_JOINACKMAC,		/* HMAC was wrong on ACK + MP_JOIN */
 	MPTCP_MIB_DSSNOMATCH,		/* Received a new mapping that did not match the previous one */
+	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 */
 	MPTCP_MIB_DATACSUMERR,		/* The data checksum fail */
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 161c07f49db6..4581c570ef68 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1239,6 +1239,7 @@ static void mptcp_update_infinite_map(struct mptcp_sock *msk,
 	mpext->infinite_map = 1;
 	mpext->data_len = 0;
 
+	MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPTX);
 	mptcp_subflow_ctx(ssk)->send_infinite_map = 0;
 	pr_fallback(msk);
 	__mptcp_do_fallback(msk);
-- 
2.36.0

[PATCH net-next 7/8] mptcp: dump infinite_map field in mptcp_dump_mpext

[Mat Martineau]

From: Geliang Tang <geliang.tang@suse.com>

In trace event class mptcp_dump_mpext, dump the newly added infinite_map
field of struct mptcp_dump_mpext too.

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 include/trace/events/mptcp.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/trace/events/mptcp.h b/include/trace/events/mptcp.h
index f8e28e686c65..563e48617374 100644
--- a/include/trace/events/mptcp.h
+++ b/include/trace/events/mptcp.h
@@ -84,6 +84,7 @@ DECLARE_EVENT_CLASS(mptcp_dump_mpext,
 		__field(u8, reset_transient)
 		__field(u8, reset_reason)
 		__field(u8, csum_reqd)
+		__field(u8, infinite_map)
 	),
 
 	TP_fast_assign(
@@ -102,9 +103,10 @@ DECLARE_EVENT_CLASS(mptcp_dump_mpext,
 		__entry->reset_transient = mpext->reset_transient;
 		__entry->reset_reason = mpext->reset_reason;
 		__entry->csum_reqd = mpext->csum_reqd;
+		__entry->infinite_map = mpext->infinite_map;
 	),
 
-	TP_printk("data_ack=%llu data_seq=%llu subflow_seq=%u data_len=%u csum=%x use_map=%u dsn64=%u data_fin=%u use_ack=%u ack64=%u mpc_map=%u frozen=%u reset_transient=%u reset_reason=%u csum_reqd=%u",
+	TP_printk("data_ack=%llu data_seq=%llu subflow_seq=%u data_len=%u csum=%x use_map=%u dsn64=%u data_fin=%u use_ack=%u ack64=%u mpc_map=%u frozen=%u reset_transient=%u reset_reason=%u csum_reqd=%u infinite_map=%u",
 		  __entry->data_ack, __entry->data_seq,
 		  __entry->subflow_seq, __entry->data_len,
 		  __entry->csum, __entry->use_map,
@@ -112,7 +114,7 @@ DECLARE_EVENT_CLASS(mptcp_dump_mpext,
 		  __entry->use_ack, __entry->ack64,
 		  __entry->mpc_map, __entry->frozen,
 		  __entry->reset_transient, __entry->reset_reason,
-		  __entry->csum_reqd)
+		  __entry->csum_reqd, __entry->infinite_map)
 );
 
 DEFINE_EVENT(mptcp_dump_mpext, mptcp_sendmsg_frag,
-- 
2.36.0

[PATCH net-next 8/8] selftests: mptcp: add infinite map mibs check

[Mat Martineau]

From: Geliang Tang <geliang.tang@suse.com>

This patch adds a function chk_infi_nr() to check the mibs for the
infinite mapping. Invoke it in chk_join_nr() when validate_checksum
is set.

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 .../testing/selftests/net/mptcp/mptcp_join.sh | 36 ++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index 7314257d248a..9eb4d889a24a 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -1106,6 +1106,38 @@ chk_rst_nr()
 	echo "$extra_msg"
 }
 
+chk_infi_nr()
+{
+	local infi_tx=$1
+	local infi_rx=$2
+	local count
+	local dump_stats
+
+	printf "%-${nr_blank}s %s" " " "itx"
+	count=$(ip netns exec $ns2 nstat -as | grep InfiniteMapTx | awk '{print $2}')
+	[ -z "$count" ] && count=0
+	if [ "$count" != "$infi_tx" ]; then
+		echo "[fail] got $count infinite map[s] TX expected $infi_tx"
+		fail_test
+		dump_stats=1
+	else
+		echo -n "[ ok ]"
+	fi
+
+	echo -n " - infirx"
+	count=$(ip netns exec $ns1 nstat -as | grep InfiniteMapRx | awk '{print $2}')
+	[ -z "$count" ] && count=0
+	if [ "$count" != "$infi_rx" ]; then
+		echo "[fail] got $count infinite map[s] RX expected $infi_rx"
+		fail_test
+		dump_stats=1
+	else
+		echo "[ ok ]"
+	fi
+
+	[ "${dump_stats}" = 1 ] && dump_stats
+}
+
 chk_join_nr()
 {
 	local syn_nr=$1
@@ -1115,7 +1147,8 @@ chk_join_nr()
 	local csum_ns2=${5:-0}
 	local fail_nr=${6:-0}
 	local rst_nr=${7:-0}
-	local corrupted_pkts=${8:-0}
+	local infi_nr=${8:-0}
+	local corrupted_pkts=${9:-0}
 	local count
 	local dump_stats
 	local with_cookie
@@ -1170,6 +1203,7 @@ chk_join_nr()
 		chk_csum_nr $csum_ns1 $csum_ns2
 		chk_fail_nr $fail_nr $fail_nr
 		chk_rst_nr $rst_nr $rst_nr
+		chk_infi_nr $infi_nr $infi_nr
 	fi
 }
 
-- 
2.36.0

Re: [PATCH net-next 0/8] mptcp: TCP fallback for established connections

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (master)
by David S. Miller <davem@davemloft.net>:

On Fri, 22 Apr 2022 14:55:35 -0700 you wrote:
> RFC 8684 allows some MPTCP connections to fall back to regular TCP when
> the MPTCP DSS checksum detects middlebox interference, there is only a
> single subflow, and there is no unacknowledged out-of-sequence
> data. When this condition is detected, the stack sends a MPTCP DSS
> option with an "infinite mapping" to signal that a fallback is
> happening, and the peers will stop sending MPTCP options in their TCP
> headers. The Linux MPTCP stack has not yet supported this type of
> fallback, instead closing the connection when the MPTCP checksum fails.
> 
> [...]

Here is the summary with links:
  - [net-next,1/8] mptcp: don't send RST for single subflow
    https://git.kernel.org/netdev/net-next/c/1761fed25678
  - [net-next,2/8] mptcp: add the fallback check
    https://git.kernel.org/netdev/net-next/c/0348c690ed37
  - [net-next,3/8] mptcp: track and update contiguous data status
    https://git.kernel.org/netdev/net-next/c/0530020a7c8f
  - [net-next,4/8] mptcp: infinite mapping sending
    https://git.kernel.org/netdev/net-next/c/1e39e5a32ad7
  - [net-next,5/8] mptcp: infinite mapping receiving
    https://git.kernel.org/netdev/net-next/c/f8d4bcacff3b
  - [net-next,6/8] mptcp: add mib for infinite map sending
    https://git.kernel.org/netdev/net-next/c/104125b82e5c
  - [net-next,7/8] mptcp: dump infinite_map field in mptcp_dump_mpext
    https://git.kernel.org/netdev/net-next/c/d9fdd02d4265
  - [net-next,8/8] selftests: mptcp: add infinite map mibs check
    https://git.kernel.org/netdev/net-next/c/8bd03be3418c

You are awesome, thank you!
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