Merge branch 'mptcp-miscellaneous-mptcp-fixes'

Mat Martineau says:

====================
mptcp: Miscellaneous MPTCP fixes

This is a collection of small fixup and minor enhancement patches that
have accumulated in the MPTCP tree while net-next was closed. These are
prerequisites for larger changes we have queued up.

Patch 1 refines receive buffer autotuning.

Patches 2 and 4 are some minor locking and refactoring changes.

Patch 3 improves GRO and RX coalescing with MPTCP skbs.

Patches 5-7 add a sysctl for tuning ADD_ADDR retransmission timeout,
corresponding test code, and documentation.

v2: Add sysctl documentation and fix signoff tags.
====================

Link: https://lore.kernel.org/r/20201103190509.27416-1-mathew.j.martineau@linux.intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/networking/index.rst

@@ -70,6 +70,7 @@ Contents:
    lapb-module
    mac80211-injection
    mpls-sysctl
+   mptcp-sysctl
    multiqueue
    netconsole
    netdev-features

Documentation/networking/mptcp-sysctl.rst

@@ -0,0 +1,26 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=====================
+MPTCP Sysfs variables
+=====================
+
+/proc/sys/net/mptcp/* Variables
+===============================
+
+enabled - INTEGER
+	Control whether MPTCP sockets can be created.
+
+	MPTCP sockets can be created if the value is nonzero. This is
+	a per-namespace sysctl.
+
+	Default: 1
+
+add_addr_timeout - INTEGER (seconds)
+	Set the timeout after which an ADD_ADDR control message will be
+	resent to an MPTCP peer that has not acknowledged a previous
+	ADD_ADDR message.
+
+	The default value matches TCP_RTO_MAX. This is a per-namespace
+	sysctl.
+
+	Default: 120

MAINTAINERS

@@ -12265,6 +12265,7 @@ L:	mptcp@lists.01.org
 S:	Maintained
 W:	https://github.com/multipath-tcp/mptcp_net-next/wiki
 B:	https://github.com/multipath-tcp/mptcp_net-next/issues
+F:	Documentation/networking/mptcp-sysctl.rst
 F:	include/net/mptcp.h
 F:	include/uapi/linux/mptcp.h
 F:	net/mptcp/

include/net/mptcp.h

@@ -29,7 +29,8 @@ struct mptcp_ext {
 			use_ack:1,
 			ack64:1,
 			mpc_map:1,
-			__unused:2;
+			frozen:1,
+			__unused:1;
 	/* one byte hole */
 };
 
@@ -106,6 +107,19 @@ static inline void mptcp_skb_ext_move(struct sk_buff *to,
 	from->active_extensions = 0;
 }
 
+static inline void mptcp_skb_ext_copy(struct sk_buff *to,
+				      struct sk_buff *from)
+{
+	struct mptcp_ext *from_ext;
+
+	from_ext = skb_ext_find(from, SKB_EXT_MPTCP);
+	if (!from_ext)
+		return;
+
+	from_ext->frozen = 1;
+	skb_ext_copy(to, from);
+}
+
 static inline bool mptcp_ext_matches(const struct mptcp_ext *to_ext,
 				     const struct mptcp_ext *from_ext)
 {
@@ -193,6 +207,11 @@ static inline void mptcp_skb_ext_move(struct sk_buff *to,
 {
 }
 
+static inline void mptcp_skb_ext_copy(struct sk_buff *to,
+				      struct sk_buff *from)
+{
+}
+
 static inline bool mptcp_skb_can_collapse(const struct sk_buff *to,
 					  const struct sk_buff *from)
 {

net/ipv4/tcp_output.c

@@ -1569,6 +1569,7 @@ int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
 	if (!buff)
 		return -ENOMEM; /* We'll just try again later. */
 	skb_copy_decrypted(buff, skb);
+	mptcp_skb_ext_copy(buff, skb);
 
 	sk_wmem_queued_add(sk, buff->truesize);
 	sk_mem_charge(sk, buff->truesize);
@@ -2123,6 +2124,7 @@ static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len,
 	if (unlikely(!buff))
 		return -ENOMEM;
 	skb_copy_decrypted(buff, skb);
+	mptcp_skb_ext_copy(buff, skb);
 
 	sk_wmem_queued_add(sk, buff->truesize);
 	sk_mem_charge(sk, buff->truesize);
@@ -2393,6 +2395,7 @@ static int tcp_mtu_probe(struct sock *sk)
 
 	skb = tcp_send_head(sk);
 	skb_copy_decrypted(nskb, skb);
+	mptcp_skb_ext_copy(nskb, skb);
 
 	TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq;
 	TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size;

net/mptcp/ctrl.c

@@ -18,6 +18,7 @@ struct mptcp_pernet {
 	struct ctl_table_header *ctl_table_hdr;
 
 	int mptcp_enabled;
+	unsigned int add_addr_timeout;
 };
 
 static struct mptcp_pernet *mptcp_get_pernet(struct net *net)
@@ -30,6 +31,11 @@ int mptcp_is_enabled(struct net *net)
 	return mptcp_get_pernet(net)->mptcp_enabled;
 }
 
+unsigned int mptcp_get_add_addr_timeout(struct net *net)
+{
+	return mptcp_get_pernet(net)->add_addr_timeout;
+}
+
 static struct ctl_table mptcp_sysctl_table[] = {
 	{
 		.procname = "enabled",
@@ -40,12 +46,19 @@ static struct ctl_table mptcp_sysctl_table[] = {
 		 */
 		.proc_handler = proc_dointvec,
 	},
+	{
+		.procname = "add_addr_timeout",
+		.maxlen = sizeof(unsigned int),
+		.mode = 0644,
+		.proc_handler = proc_dointvec_jiffies,
+	},
 	{}
 };
 
 static void mptcp_pernet_set_defaults(struct mptcp_pernet *pernet)
 {
 	pernet->mptcp_enabled = 1;
+	pernet->add_addr_timeout = TCP_RTO_MAX;
 }
 
 static int mptcp_pernet_new_table(struct net *net, struct mptcp_pernet *pernet)
@@ -61,6 +74,7 @@ static int mptcp_pernet_new_table(struct net *net, struct mptcp_pernet *pernet)
 	}
 
 	table[0].data = &pernet->mptcp_enabled;
+	table[1].data = &pernet->add_addr_timeout;
 
 	hdr = register_net_sysctl(net, MPTCP_SYSCTL_PATH, table);
 	if (!hdr)

net/mptcp/pm_netlink.c

@@ -206,6 +206,7 @@ static void mptcp_pm_add_timer(struct timer_list *timer)
 	struct mptcp_pm_add_entry *entry = from_timer(entry, timer, add_timer);
 	struct mptcp_sock *msk = entry->sock;
 	struct sock *sk = (struct sock *)msk;
+	struct net *net = sock_net(sk);
 
 	pr_debug("msk=%p", msk);
 
@@ -232,7 +233,8 @@ static void mptcp_pm_add_timer(struct timer_list *timer)
 	}
 
 	if (entry->retrans_times < ADD_ADDR_RETRANS_MAX)
-		sk_reset_timer(sk, timer, jiffies + TCP_RTO_MAX);
+		sk_reset_timer(sk, timer,
+			       jiffies + mptcp_get_add_addr_timeout(net));
 
 	spin_unlock_bh(&msk->pm.lock);
 
@@ -264,6 +266,7 @@ static bool mptcp_pm_alloc_anno_list(struct mptcp_sock *msk,
 {
 	struct mptcp_pm_add_entry *add_entry = NULL;
 	struct sock *sk = (struct sock *)msk;
+	struct net *net = sock_net(sk);
 
 	if (lookup_anno_list_by_saddr(msk, &entry->addr))
 		return false;
@@ -279,7 +282,8 @@ static bool mptcp_pm_alloc_anno_list(struct mptcp_sock *msk,
 	add_entry->retrans_times = 0;
 
 	timer_setup(&add_entry->add_timer, mptcp_pm_add_timer, 0);
-	sk_reset_timer(sk, &add_entry->add_timer, jiffies + TCP_RTO_MAX);
+	sk_reset_timer(sk, &add_entry->add_timer,
+		       jiffies + mptcp_get_add_addr_timeout(net));
 
 	return true;
 }

net/mptcp/protocol.c

@@ -466,6 +466,18 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk,
 	struct tcp_sock *tp;
 	u32 old_copied_seq;
 	bool done = false;
+	int sk_rbuf;
+
+	sk_rbuf = READ_ONCE(sk->sk_rcvbuf);
+
+	if (!(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {
+		int ssk_rbuf = READ_ONCE(ssk->sk_rcvbuf);
+
+		if (unlikely(ssk_rbuf > sk_rbuf)) {
+			WRITE_ONCE(sk->sk_rcvbuf, ssk_rbuf);
+			sk_rbuf = ssk_rbuf;
+		}
+	}
 
 	pr_debug("msk=%p ssk=%p", msk, ssk);
 	tp = tcp_sk(ssk);
@@ -528,7 +540,7 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk,
 		WRITE_ONCE(tp->copied_seq, seq);
 		more_data_avail = mptcp_subflow_data_available(ssk);
 
-		if (atomic_read(&sk->sk_rmem_alloc) > READ_ONCE(sk->sk_rcvbuf)) {
+		if (atomic_read(&sk->sk_rmem_alloc) > sk_rbuf) {
 			done = true;
 			break;
 		}
@@ -622,6 +634,7 @@ void mptcp_data_ready(struct sock *sk, struct sock *ssk)
 {
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 	struct mptcp_sock *msk = mptcp_sk(sk);
+	int sk_rbuf, ssk_rbuf;
 	bool wake;
 
 	/* move_skbs_to_msk below can legitly clear the data_avail flag,
@@ -632,12 +645,16 @@ void mptcp_data_ready(struct sock *sk, struct sock *ssk)
 	if (wake)
 		set_bit(MPTCP_DATA_READY, &msk->flags);
 
-	if (atomic_read(&sk->sk_rmem_alloc) < READ_ONCE(sk->sk_rcvbuf) &&
-	    move_skbs_to_msk(msk, ssk))
+	ssk_rbuf = READ_ONCE(ssk->sk_rcvbuf);
+	sk_rbuf = READ_ONCE(sk->sk_rcvbuf);
+	if (unlikely(ssk_rbuf > sk_rbuf))
+		sk_rbuf = ssk_rbuf;
+
+	/* over limit? can't append more skbs to msk */
+	if (atomic_read(&sk->sk_rmem_alloc) > sk_rbuf)
 		goto wake;
 
-	/* don't schedule if mptcp sk is (still) over limit */
-	if (atomic_read(&sk->sk_rmem_alloc) > READ_ONCE(sk->sk_rcvbuf))
+	if (move_skbs_to_msk(msk, ssk))
 		goto wake;
 
 	/* mptcp socket is owned, release_cb should retry */
@@ -754,8 +771,11 @@ static bool mptcp_skb_can_collapse_to(u64 write_seq,
 	if (!tcp_skb_can_collapse_to(skb))
 		return false;
 
-	/* can collapse only if MPTCP level sequence is in order */
-	return mpext && mpext->data_seq + mpext->data_len == write_seq;
+	/* can collapse only if MPTCP level sequence is in order and this
+	 * mapping has not been xmitted yet
+	 */
+	return mpext && mpext->data_seq + mpext->data_len == write_seq &&
+	       !mpext->frozen;
 }
 
 static bool mptcp_frag_can_collapse_to(const struct mptcp_sock *msk,
@@ -833,19 +853,25 @@ static void mptcp_clean_una(struct sock *sk)
 	}
 
 out:
-	if (cleaned) {
+	if (cleaned)
 		sk_mem_reclaim_partial(sk);
+}
 
-		/* Only wake up writers if a subflow is ready */
-		if (mptcp_is_writeable(msk)) {
-			set_bit(MPTCP_SEND_SPACE, &mptcp_sk(sk)->flags);
-			smp_mb__after_atomic();
+static void mptcp_clean_una_wakeup(struct sock *sk)
+{
+	struct mptcp_sock *msk = mptcp_sk(sk);
 
-			/* set SEND_SPACE before sk_stream_write_space clears
-			 * NOSPACE
-			 */
-			sk_stream_write_space(sk);
-		}
+	mptcp_clean_una(sk);
+
+	/* Only wake up writers if a subflow is ready */
+	if (mptcp_is_writeable(msk)) {
+		set_bit(MPTCP_SEND_SPACE, &msk->flags);
+		smp_mb__after_atomic();
+
+		/* set SEND_SPACE before sk_stream_write_space clears
+		 * NOSPACE
+		 */
+		sk_stream_write_space(sk);
 	}
 }
 
@@ -1476,13 +1502,14 @@ static bool __mptcp_move_skbs(struct mptcp_sock *msk)
 	__mptcp_flush_join_list(msk);
 	do {
 		struct sock *ssk = mptcp_subflow_recv_lookup(msk);
+		bool slowpath;
 
 		if (!ssk)
 			break;
 
-		lock_sock(ssk);
+		slowpath = lock_sock_fast(ssk);
 		done = __mptcp_move_skbs_from_subflow(msk, ssk, &moved);
-		release_sock(ssk);
+		unlock_sock_fast(ssk, slowpath);
 	} while (!done);
 
 	if (mptcp_ofo_queue(msk) || moved > 0) {
@@ -1748,7 +1775,7 @@ static void mptcp_worker(struct work_struct *work)
 	long timeo = 0;
 
 	lock_sock(sk);
-	mptcp_clean_una(sk);
+	mptcp_clean_una_wakeup(sk);
 	mptcp_check_data_fin_ack(sk);
 	__mptcp_flush_join_list(msk);
 	if (test_and_clear_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))

net/mptcp/protocol.h

@@ -362,6 +362,7 @@ mptcp_subflow_get_mapped_dsn(const struct mptcp_subflow_context *subflow)
 }
 
 int mptcp_is_enabled(struct net *net);
+unsigned int mptcp_get_add_addr_timeout(struct net *net);
 void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
 				     struct mptcp_options_received *mp_opt);
 bool mptcp_subflow_data_available(struct sock *sk);

tools/testing/selftests/net/mptcp/config

@@ -5,3 +5,13 @@ CONFIG_INET_DIAG=m
 CONFIG_INET_MPTCP_DIAG=m
 CONFIG_VETH=y
 CONFIG_NET_SCH_NETEM=m
+CONFIG_NETFILTER=y
+CONFIG_NETFILTER_ADVANCED=y
+CONFIG_NETFILTER_NETLINK=m
+CONFIG_NF_TABLES=m
+CONFIG_NFT_COUNTER=m
+CONFIG_NFT_COMPAT=m
+CONFIG_NETFILTER_XTABLES=m
+CONFIG_NETFILTER_XT_MATCH_BPF=m
+CONFIG_NF_TABLES_IPV4=y
+CONFIG_NF_TABLES_IPV6=y

tools/testing/selftests/net/mptcp/mptcp_join.sh

@@ -13,6 +13,24 @@ capture=0
 
 TEST_COUNT=0
 
+# generated using "nfbpf_compile '(ip && (ip[54] & 0xf0) == 0x30) ||
+#				  (ip6 && (ip6[74] & 0xf0) == 0x30)'"
+CBPF_MPTCP_SUBOPTION_ADD_ADDR="14,
+			       48 0 0 0,
+			       84 0 0 240,
+			       21 0 3 64,
+			       48 0 0 54,
+			       84 0 0 240,
+			       21 6 7 48,
+			       48 0 0 0,
+			       84 0 0 240,
+			       21 0 4 96,
+			       48 0 0 74,
+			       84 0 0 240,
+			       21 0 1 48,
+			       6 0 0 65535,
+			       6 0 0 0"
+
 init()
 {
 	capout=$(mktemp)
@@ -82,6 +100,26 @@ reset_with_cookies()
 	done
 }
 
+reset_with_add_addr_timeout()
+{
+	local ip="${1:-4}"
+	local tables
+
+	tables="iptables"
+	if [ $ip -eq 6 ]; then
+		tables="ip6tables"
+	fi
+
+	reset
+
+	ip netns exec $ns1 sysctl -q net.mptcp.add_addr_timeout=1
+	ip netns exec $ns2 $tables -A OUTPUT -p tcp \
+		-m tcp --tcp-option 30 \
+		-m bpf --bytecode \
+		"$CBPF_MPTCP_SUBOPTION_ADD_ADDR" \
+		-j DROP
+}
+
 for arg in "$@"; do
 	if [ "$arg" = "-c" ]; then
 		capture=1
@@ -94,6 +132,17 @@ if [ $? -ne 0 ];then
 	exit $ksft_skip
 fi
 
+iptables -V > /dev/null 2>&1
+if [ $? -ne 0 ];then
+	echo "SKIP: Could not run all tests without iptables tool"
+	exit $ksft_skip
+fi
+
+ip6tables -V > /dev/null 2>&1
+if [ $? -ne 0 ];then
+	echo "SKIP: Could not run all tests without ip6tables tool"
+	exit $ksft_skip
+fi
 
 check_transfer()
 {
@@ -135,6 +184,7 @@ do_transfer()
 	connect_addr="$5"
 	rm_nr_ns1="$6"
 	rm_nr_ns2="$7"
+	speed="$8"
 
 	port=$((10000+$TEST_COUNT))
 	TEST_COUNT=$((TEST_COUNT+1))
@@ -159,7 +209,7 @@ do_transfer()
 		sleep 1
 	fi
 
-	if [[ $rm_nr_ns1 -eq 0 && $rm_nr_ns2 -eq 0 ]]; then
+	if [ $speed = "fast" ]; then
 		mptcp_connect="./mptcp_connect -j"
 	else
 		mptcp_connect="./mptcp_connect -r"
@@ -250,26 +300,13 @@ run_tests()
 	listener_ns="$1"
 	connector_ns="$2"
 	connect_addr="$3"
+	rm_nr_ns1="${4:-0}"
+	rm_nr_ns2="${5:-0}"
+	speed="${6:-fast}"
 	lret=0
 
-	do_transfer ${listener_ns} ${connector_ns} MPTCP MPTCP ${connect_addr} 0 0
-	lret=$?
-	if [ $lret -ne 0 ]; then
-		ret=$lret
-		return
-	fi
-}
-
-run_remove_tests()
-{
-	listener_ns="$1"
-	connector_ns="$2"
-	connect_addr="$3"
-	rm_nr_ns1="$4"
-	rm_nr_ns2="$5"
-	lret=0
-
-	do_transfer ${listener_ns} ${connector_ns} MPTCP MPTCP ${connect_addr} ${rm_nr_ns1} ${rm_nr_ns2}
+	do_transfer ${listener_ns} ${connector_ns} MPTCP MPTCP ${connect_addr} \
+		${rm_nr_ns1} ${rm_nr_ns2} ${speed}
 	lret=$?
 	if [ $lret -ne 0 ]; then
 		ret=$lret
@@ -491,12 +528,21 @@ run_tests $ns1 $ns2 10.0.1.1
 chk_join_nr "multiple subflows and signal" 3 3 3
 chk_add_nr 1 1
 
+# add_addr timeout
+reset_with_add_addr_timeout
+ip netns exec $ns1 ./pm_nl_ctl limits 0 1
+ip netns exec $ns2 ./pm_nl_ctl limits 1 1
+ip netns exec $ns1 ./pm_nl_ctl add 10.0.2.1 flags signal
+run_tests $ns1 $ns2 10.0.1.1 0 0 slow
+chk_join_nr "signal address, ADD_ADDR timeout" 1 1 1
+chk_add_nr 4 0
+
 # single subflow, remove
 reset
 ip netns exec $ns1 ./pm_nl_ctl limits 0 1
 ip netns exec $ns2 ./pm_nl_ctl limits 0 1
 ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags subflow
-run_remove_tests $ns1 $ns2 10.0.1.1 0 1
+run_tests $ns1 $ns2 10.0.1.1 0 1 slow
 chk_join_nr "remove single subflow" 1 1 1
 chk_rm_nr 1 1
 
@@ -506,7 +552,7 @@ ip netns exec $ns1 ./pm_nl_ctl limits 0 2
 ip netns exec $ns2 ./pm_nl_ctl limits 0 2
 ip netns exec $ns2 ./pm_nl_ctl add 10.0.2.2 flags subflow
 ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags subflow
-run_remove_tests $ns1 $ns2 10.0.1.1 0 2
+run_tests $ns1 $ns2 10.0.1.1 0 2 slow
 chk_join_nr "remove multiple subflows" 2 2 2
 chk_rm_nr 2 2
 
@@ -515,7 +561,7 @@ reset
 ip netns exec $ns1 ./pm_nl_ctl limits 0 1
 ip netns exec $ns1 ./pm_nl_ctl add 10.0.2.1 flags signal
 ip netns exec $ns2 ./pm_nl_ctl limits 1 1
-run_remove_tests $ns1 $ns2 10.0.1.1 1 0
+run_tests $ns1 $ns2 10.0.1.1 1 0 slow
 chk_join_nr "remove single address" 1 1 1
 chk_add_nr 1 1
 chk_rm_nr 0 0
@@ -526,7 +572,7 @@ ip netns exec $ns1 ./pm_nl_ctl limits 0 2
 ip netns exec $ns1 ./pm_nl_ctl add 10.0.2.1 flags signal
 ip netns exec $ns2 ./pm_nl_ctl limits 1 2
 ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags subflow
-run_remove_tests $ns1 $ns2 10.0.1.1 1 1
+run_tests $ns1 $ns2 10.0.1.1 1 1 slow
 chk_join_nr "remove subflow and signal" 2 2 2
 chk_add_nr 1 1
 chk_rm_nr 1 1
@@ -538,7 +584,7 @@ ip netns exec $ns1 ./pm_nl_ctl add 10.0.2.1 flags signal
 ip netns exec $ns2 ./pm_nl_ctl limits 1 3
 ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags subflow
 ip netns exec $ns2 ./pm_nl_ctl add 10.0.4.2 flags subflow
-run_remove_tests $ns1 $ns2 10.0.1.1 1 2
+run_tests $ns1 $ns2 10.0.1.1 1 2 slow
 chk_join_nr "remove subflows and signal" 3 3 3
 chk_add_nr 1 1
 chk_rm_nr 2 2