[MPTCP][PATCH v3 mptcp-next 0/4] add MP_CAPABLE 'C' flag

[MPTCP][PATCH v3 mptcp-next 0/4] add MP_CAPABLE 'C' flag

[Geliang Tang]

v3:
 - use 'u8 allow_join_initial_addr_port'
 - drop the spinlock in patch 3

v2:
 - rename join_denied to allow_join_id0 in mptcp_out_options
 - rename join_denied to deny_join_id0 in mptcp_options_received
 - add a new function mptcp_pm_deny_join_id0_received
 - move deny_join_id0 flag from mptcp_sock to mptcp_pm_data
 - check deny_join_id0 flag in mptcp_pm_create_subflow_or_signal_addr
instead of in mptcp_syn_options.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/183

Geliang Tang (4):
  mptcp: add sysctl allow_join_initial_addr_port
  mptcp: add allow_join_id0 in mptcp_out_options
  mptcp: add deny_join_id0 in mptcp_options_received
  selftests: mptcp: add deny_join_id0 testcases

 Documentation/networking/mptcp-sysctl.rst     | 13 +++++
 include/net/mptcp.h                           |  3 +-
 net/mptcp/ctrl.c                              | 16 ++++++
 net/mptcp/options.c                           | 16 +++++-
 net/mptcp/pm.c                                |  1 +
 net/mptcp/pm_netlink.c                        |  4 +-
 net/mptcp/protocol.h                          | 11 +++-
 net/mptcp/subflow.c                           |  3 +
 .../testing/selftests/net/mptcp/mptcp_join.sh | 55 ++++++++++++++++++-
 9 files changed, 114 insertions(+), 8 deletions(-)

-- 
2.30.2

[MPTCP][PATCH v3 mptcp-next 1/4] mptcp: add sysctl allow_join_initial_addr_port

[Geliang Tang]

This patch added a new sysctl, named allow_join_initial_addr_port, to
control whether allow peers to send join requests to the IP address and
port number used by the initial subflow.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
---
 Documentation/networking/mptcp-sysctl.rst | 13 +++++++++++++
 net/mptcp/ctrl.c                          | 16 ++++++++++++++++
 net/mptcp/protocol.h                      |  1 +
 3 files changed, 30 insertions(+)

diff --git a/Documentation/networking/mptcp-sysctl.rst b/Documentation/networking/mptcp-sysctl.rst
index 3b352e5f6300..6c67ea3d0b7f 100644
--- a/Documentation/networking/mptcp-sysctl.rst
+++ b/Documentation/networking/mptcp-sysctl.rst
@@ -24,3 +24,16 @@ add_addr_timeout - INTEGER (seconds)
 	sysctl.
 
 	Default: 120
+
+allow_join_initial_addr_port - INTEGER
+	Allow peers to send join requests to the IP address and port number used
+	by the initial subflow if the value is 1. This controls a flag that is
+	sent to the peer at connection time, and whether such join requests are
+	accepted or denied.
+
+	Joins to addresses advertised with ADD_ADDR are not affected by this
+	value.
+
+	This is a per-namespace sysctl.
+
+	Default: 1
diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
index 08c152199b89..5c520fcdf93d 100644
--- a/net/mptcp/ctrl.c
+++ b/net/mptcp/ctrl.c
@@ -19,6 +19,7 @@ struct mptcp_pernet {
 
 	u8 mptcp_enabled;
 	unsigned int add_addr_timeout;
+	u8 allow_join_initial_addr_port;
 };
 
 static struct mptcp_pernet *mptcp_get_pernet(struct net *net)
@@ -36,6 +37,11 @@ unsigned int mptcp_get_add_addr_timeout(struct net *net)
 	return mptcp_get_pernet(net)->add_addr_timeout;
 }
 
+int mptcp_is_allow_join_id0(struct net *net)
+{
+	return mptcp_get_pernet(net)->allow_join_initial_addr_port;
+}
+
 static struct ctl_table mptcp_sysctl_table[] = {
 	{
 		.procname = "enabled",
@@ -54,6 +60,14 @@ static struct ctl_table mptcp_sysctl_table[] = {
 		.mode = 0644,
 		.proc_handler = proc_dointvec_jiffies,
 	},
+	{
+		.procname = "allow_join_initial_addr_port",
+		.maxlen = sizeof(u8),
+		.mode = 0644,
+		.proc_handler = proc_dou8vec_minmax,
+		.extra1       = SYSCTL_ZERO,
+		.extra2       = SYSCTL_ONE
+	},
 	{}
 };
 
@@ -61,6 +75,7 @@ static void mptcp_pernet_set_defaults(struct mptcp_pernet *pernet)
 {
 	pernet->mptcp_enabled = 1;
 	pernet->add_addr_timeout = TCP_RTO_MAX;
+	pernet->allow_join_initial_addr_port = 1;
 }
 
 static int mptcp_pernet_new_table(struct net *net, struct mptcp_pernet *pernet)
@@ -77,6 +92,7 @@ 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;
+	table[2].data = &pernet->allow_join_initial_addr_port;
 
 	hdr = register_net_sysctl(net, MPTCP_SYSCTL_PATH, table);
 	if (!hdr)
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index d230a75af631..bb901435c2d4 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -524,6 +524,7 @@ static inline void mptcp_subflow_delegated_done(struct mptcp_subflow_context *su
 
 int mptcp_is_enabled(struct net *net);
 unsigned int mptcp_get_add_addr_timeout(struct net *net);
+int mptcp_is_allow_join_id0(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);
-- 
2.30.2

[MPTCP][PATCH v3 mptcp-next 2/4] mptcp: add allow_join_id0 in mptcp_out_options

[Geliang Tang]

This patch defined a new flag MPTCP_CAP_DENY_JOIN_ID0 for the third bit,
labeled "C" of the MP_CAPABLE option.

Add a new flag allow_join_id0 in struct mptcp_out_options. If this flag is
set, send out the MP_CAPABLE option with the flag MPTCP_CAP_DENY_JOIN_ID0.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
---
 include/net/mptcp.h  |  3 ++-
 net/mptcp/options.c  | 10 ++++++++--
 net/mptcp/protocol.h |  6 ++++--
 net/mptcp/subflow.c  |  1 +
 4 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 83f23774b908..d259796326ea 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -64,7 +64,8 @@ struct mptcp_out_options {
 	u8 join_id;
 	u8 backup;
 	u8 reset_reason:4;
-	u8 reset_transient:1;
+	u8 reset_transient:1,
+	   allow_join_id0:1;
 	u32 nonce;
 	u64 thmac;
 	u32 token;
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 99fc21406168..58ea22bf3d3d 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -381,6 +381,7 @@ bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
 	subflow->snd_isn = TCP_SKB_CB(skb)->end_seq;
 	if (subflow->request_mptcp) {
 		opts->suboptions = OPTION_MPTCP_MPC_SYN;
+		opts->allow_join_id0 = mptcp_is_allow_join_id0(sock_net(sk));
 		*size = TCPOLEN_MPTCP_MPC_SYN;
 		return true;
 	} else if (subflow->request_join) {
@@ -466,6 +467,7 @@ static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb,
 		opts->suboptions = OPTION_MPTCP_MPC_ACK;
 		opts->sndr_key = subflow->local_key;
 		opts->rcvr_key = subflow->remote_key;
+		opts->allow_join_id0 = mptcp_is_allow_join_id0(sock_net(sk));
 
 		/* Section 3.1.
 		 * The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK
@@ -790,6 +792,7 @@ bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
 	if (subflow_req->mp_capable) {
 		opts->suboptions = OPTION_MPTCP_MPC_SYNACK;
 		opts->sndr_key = subflow_req->local_key;
+		opts->allow_join_id0 = subflow_req->allow_join_id0;
 		*size = TCPOLEN_MPTCP_MPC_SYNACK;
 		pr_debug("subflow_req=%p, local_key=%llu",
 			 subflow_req, subflow_req->local_key);
@@ -1124,7 +1127,7 @@ void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
 {
 	if ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK |
 	     OPTION_MPTCP_MPC_ACK) & opts->suboptions) {
-		u8 len;
+		u8 len, flag = MPTCP_CAP_HMAC_SHA256;
 
 		if (OPTION_MPTCP_MPC_SYN & opts->suboptions)
 			len = TCPOLEN_MPTCP_MPC_SYN;
@@ -1135,9 +1138,12 @@ void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
 		else
 			len = TCPOLEN_MPTCP_MPC_ACK;
 
+		if (!opts->allow_join_id0)
+			flag |= MPTCP_CAP_DENY_JOIN_ID0;
+
 		*ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len,
 				      MPTCP_SUPPORTED_VERSION,
-				      MPTCP_CAP_HMAC_SHA256);
+				      flag);
 
 		if (!((OPTION_MPTCP_MPC_SYNACK | OPTION_MPTCP_MPC_ACK) &
 		    opts->suboptions))
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index bb901435c2d4..fcbaf47ce3bc 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -77,8 +77,9 @@
 #define MPTCP_VERSION_MASK	(0x0F)
 #define MPTCP_CAP_CHECKSUM_REQD	BIT(7)
 #define MPTCP_CAP_EXTENSIBILITY	BIT(6)
+#define MPTCP_CAP_DENY_JOIN_ID0	BIT(5)
 #define MPTCP_CAP_HMAC_SHA256	BIT(0)
-#define MPTCP_CAP_FLAG_MASK	(0x3F)
+#define MPTCP_CAP_FLAG_MASK	(0x1F)
 
 /* MPTCP DSS flags */
 #define MPTCP_DSS_DATA_FIN	BIT(4)
@@ -338,7 +339,8 @@ struct mptcp_subflow_request_sock {
 	struct	tcp_request_sock sk;
 	u16	mp_capable : 1,
 		mp_join : 1,
-		backup : 1;
+		backup : 1,
+		allow_join_id0 : 1;
 	u8	local_id;
 	u8	remote_id;
 	u64	local_key;
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 15620bafc544..fb5b6eb5bec9 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -108,6 +108,7 @@ static void subflow_init_req(struct request_sock *req, const struct sock *sk_lis
 
 	subflow_req->mp_capable = 0;
 	subflow_req->mp_join = 0;
+	subflow_req->allow_join_id0 = mptcp_is_allow_join_id0(sock_net(sk_listener));
 	subflow_req->msk = NULL;
 	mptcp_token_init_request(req);
 }
-- 
2.30.2

[MPTCP][PATCH v3 mptcp-next 3/4] mptcp: add deny_join_id0 in mptcp_options_received

[Geliang Tang]

This patch added a new flag named deny_join_id0 in struct
mptcp_options_received. Set it when MP_CAPABLE with the flag
MPTCP_CAP_DENYJOIN_ID0 is received.

Also add a new flag deny_join_id0 in struct mptcp_pm_data. When the flag
mp_opt.deny_join_id0 is set, set this pm->deny_join_id0 flag.

In mptcp_pm_create_subflow_or_signal_addr, if the pm->deny_join_id0 flag
is set, and the remote address id is zero, stop this connection.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
---
 net/mptcp/options.c    | 6 ++++++
 net/mptcp/pm.c         | 1 +
 net/mptcp/pm_netlink.c | 4 +++-
 net/mptcp/protocol.h   | 4 +++-
 net/mptcp/subflow.c    | 2 ++
 5 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 58ea22bf3d3d..4b6c58a13864 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -77,6 +77,9 @@ static void mptcp_parse_option(const struct sk_buff *skb,
 		if (flags & MPTCP_CAP_CHECKSUM_REQD)
 			break;
 
+		if (flags & MPTCP_CAP_DENY_JOIN_ID0)
+			mp_opt->deny_join_id0 = 1;
+
 		mp_opt->mp_capable = 1;
 		if (opsize >= TCPOLEN_MPTCP_MPC_SYNACK) {
 			mp_opt->sndr_key = get_unaligned_be64(ptr);
@@ -342,6 +345,7 @@ void mptcp_get_options(const struct sk_buff *skb,
 	mp_opt->dss = 0;
 	mp_opt->mp_prio = 0;
 	mp_opt->reset = 0;
+	mp_opt->deny_join_id0 = 0;
 
 	length = (th->doff * 4) - sizeof(struct tcphdr);
 	ptr = (const unsigned char *)(th + 1);
@@ -1012,6 +1016,8 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
 	}
 
 	mptcp_get_options(skb, &mp_opt);
+	if (mp_opt.deny_join_id0)
+		WRITE_ONCE(msk->pm.deny_join_id0, true);
 	if (!check_fully_established(msk, sk, subflow, skb, &mp_opt))
 		return;
 
diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 9d00fa6d22e9..d79f015af525 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -320,6 +320,7 @@ void mptcp_pm_data_init(struct mptcp_sock *msk)
 	WRITE_ONCE(msk->pm.addr_signal, 0);
 	WRITE_ONCE(msk->pm.accept_addr, false);
 	WRITE_ONCE(msk->pm.accept_subflow, false);
+	WRITE_ONCE(msk->pm.deny_join_id0, false);
 	msk->pm.status = 0;
 
 	spin_lock_init(&msk->pm.lock);
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index d094588afad8..1491a759a04a 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -456,10 +456,12 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
 		if (local) {
 			struct mptcp_addr_info remote = { 0 };
 
+			remote_address((struct sock_common *)sk, &remote);
+			if (!remote.id && READ_ONCE(msk->pm.deny_join_id0))
+				return;
 			msk->pm.local_addr_used++;
 			msk->pm.subflows++;
 			check_work_pending(msk);
-			remote_address((struct sock_common *)sk, &remote);
 			spin_unlock_bh(&msk->pm.lock);
 			__mptcp_subflow_connect(sk, &local->addr, &remote,
 						local->flags, local->ifindex);
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index fcbaf47ce3bc..baf21c53fb42 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -134,7 +134,8 @@ struct mptcp_options_received {
 		rm_addr : 1,
 		mp_prio : 1,
 		echo : 1,
-		backup : 1;
+		backup : 1,
+		deny_join_id0 : 1;
 	u32	token;
 	u32	nonce;
 	u64	thmac;
@@ -189,6 +190,7 @@ struct mptcp_pm_data {
 	bool		work_pending;
 	bool		accept_addr;
 	bool		accept_subflow;
+	bool		deny_join_id0;
 	u8		add_addr_signaled;
 	u8		add_addr_accepted;
 	u8		local_addr_used;
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index fb5b6eb5bec9..2de3b91d1626 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -405,6 +405,8 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 			goto fallback;
 		}
 
+		if (mp_opt.deny_join_id0)
+			WRITE_ONCE(mptcp_sk(parent)->pm.deny_join_id0, true);
 		subflow->mp_capable = 1;
 		subflow->can_ack = 1;
 		subflow->remote_key = mp_opt.sndr_key;
-- 
2.30.2

[MPTCP][PATCH v3 mptcp-next 4/4] selftests: mptcp: add deny_join_id0 testcases

[Geliang Tang]

This patch added a new argument '-d' for mptcp_join.sh script, to invoke
the testcases for the MP_CAPABLE 'C' flag.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
---
 .../testing/selftests/net/mptcp/mptcp_join.sh | 55 ++++++++++++++++++-
 1 file changed, 54 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index fd99485cf2a4..feabc3ab88eb 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -124,6 +124,17 @@ reset_with_add_addr_timeout()
 		-j DROP
 }
 
+reset_with_allow_join_id0()
+{
+	local ns1_enable=$1
+	local ns2_enable=$2
+
+	reset
+
+	ip netns exec $ns1 sysctl -q net.mptcp.allow_join_initial_addr_port=$ns1_enable
+	ip netns exec $ns2 sysctl -q net.mptcp.allow_join_initial_addr_port=$ns2_enable
+}
+
 ip -Version > /dev/null 2>&1
 if [ $? -ne 0 ];then
 	echo "SKIP: Could not run test without ip tool"
@@ -1374,6 +1385,43 @@ syncookies_tests()
 	chk_add_nr 1 1
 }
 
+deny_join_id0_tests()
+{
+	# subflow allow join id0 ns1
+	reset_with_allow_join_id0 1 0
+	ip netns exec $ns1 ./pm_nl_ctl limits 1 1
+	ip netns exec $ns2 ./pm_nl_ctl limits 1 1
+	ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags subflow
+	run_tests $ns1 $ns2 10.0.1.1
+	chk_join_nr "single subflow allow join id0 ns1" 1 1 1
+
+	# subflow allow join id0 ns2
+	reset_with_allow_join_id0 0 1
+	ip netns exec $ns1 ./pm_nl_ctl limits 1 1
+	ip netns exec $ns2 ./pm_nl_ctl limits 1 1
+	ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags subflow
+	run_tests $ns1 $ns2 10.0.1.1
+	chk_join_nr "single subflow allow join id0 ns2" 0 0 0
+
+	# signal address allow join id0 ns1
+	reset_with_allow_join_id0 1 0
+	ip netns exec $ns1 ./pm_nl_ctl limits 1 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
+	chk_join_nr "signal address allow join id0 ns1" 1 1 1
+	chk_add_nr 1 1
+
+	# signal address allow join id0 ns2
+	reset_with_allow_join_id0 0 1
+	ip netns exec $ns1 ./pm_nl_ctl limits 1 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
+	chk_join_nr "signal address allow join id0 ns2" 1 1 1
+	chk_add_nr 1 1
+}
+
 all_tests()
 {
 	subflows_tests
@@ -1387,6 +1435,7 @@ all_tests()
 	backup_tests
 	add_addr_ports_tests
 	syncookies_tests
+	deny_join_id0_tests
 }
 
 usage()
@@ -1403,6 +1452,7 @@ usage()
 	echo "  -b backup_tests"
 	echo "  -p add_addr_ports_tests"
 	echo "  -k syncookies_tests"
+	echo "  -d deny_join_id0_tests"
 	echo "  -c capture pcap files"
 	echo "  -h help"
 }
@@ -1434,7 +1484,7 @@ if [ $do_all_tests -eq 1 ]; then
 	exit $ret
 fi
 
-while getopts 'fsltra64bpkch' opt; do
+while getopts 'fsltra64bpkdch' opt; do
 	case $opt in
 		f)
 			subflows_tests
@@ -1469,6 +1519,9 @@ while getopts 'fsltra64bpkch' opt; do
 		k)
 			syncookies_tests
 			;;
+		d)
+			deny_join_id0_tests
+			;;
 		c)
 			;;
 		h | *)
-- 
2.30.2

Re: [MPTCP][PATCH v3 mptcp-next 2/4] mptcp: add allow_join_id0 in mptcp_out_options

[Mat Martineau]

On Wed, 28 Apr 2021, Geliang Tang wrote:

> This patch defined a new flag MPTCP_CAP_DENY_JOIN_ID0 for the third bit,
> labeled "C" of the MP_CAPABLE option.
>
> Add a new flag allow_join_id0 in struct mptcp_out_options. If this flag is
> set, send out the MP_CAPABLE option with the flag MPTCP_CAP_DENY_JOIN_ID0.
>
> Signed-off-by: Geliang Tang <geliangtang@gmail.com>
> ---
> include/net/mptcp.h  |  3 ++-
> net/mptcp/options.c  | 10 ++++++++--
> net/mptcp/protocol.h |  6 ++++--
> net/mptcp/subflow.c  |  1 +
> 4 files changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/include/net/mptcp.h b/include/net/mptcp.h
> index 83f23774b908..d259796326ea 100644
> --- a/include/net/mptcp.h
> +++ b/include/net/mptcp.h
> @@ -64,7 +64,8 @@ struct mptcp_out_options {
> 	u8 join_id;
> 	u8 backup;
> 	u8 reset_reason:4;
> -	u8 reset_transient:1;
> +	u8 reset_transient:1,
> +	   allow_join_id0:1;

The bitfield declarations should be consistent here, either:

 	u8 reset_reason:4;
 	u8 reset_transient:1;
 	u8 allow_join_id0:1;

or:

 	u8 reset_reason:4,
 	   reset_transient:1,
 	   allow_join_id0:1;


Thanks,
Mat

> 	u32 nonce;
> 	u64 thmac;
> 	u32 token;
> diff --git a/net/mptcp/options.c b/net/mptcp/options.c
> index 99fc21406168..58ea22bf3d3d 100644
> --- a/net/mptcp/options.c
> +++ b/net/mptcp/options.c
> @@ -381,6 +381,7 @@ bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
> 	subflow->snd_isn = TCP_SKB_CB(skb)->end_seq;
> 	if (subflow->request_mptcp) {
> 		opts->suboptions = OPTION_MPTCP_MPC_SYN;
> +		opts->allow_join_id0 = mptcp_is_allow_join_id0(sock_net(sk));
> 		*size = TCPOLEN_MPTCP_MPC_SYN;
> 		return true;
> 	} else if (subflow->request_join) {
> @@ -466,6 +467,7 @@ static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb,
> 		opts->suboptions = OPTION_MPTCP_MPC_ACK;
> 		opts->sndr_key = subflow->local_key;
> 		opts->rcvr_key = subflow->remote_key;
> +		opts->allow_join_id0 = mptcp_is_allow_join_id0(sock_net(sk));
>
> 		/* Section 3.1.
> 		 * The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK
> @@ -790,6 +792,7 @@ bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
> 	if (subflow_req->mp_capable) {
> 		opts->suboptions = OPTION_MPTCP_MPC_SYNACK;
> 		opts->sndr_key = subflow_req->local_key;
> +		opts->allow_join_id0 = subflow_req->allow_join_id0;
> 		*size = TCPOLEN_MPTCP_MPC_SYNACK;
> 		pr_debug("subflow_req=%p, local_key=%llu",
> 			 subflow_req, subflow_req->local_key);
> @@ -1124,7 +1127,7 @@ void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
> {
> 	if ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK |
> 	     OPTION_MPTCP_MPC_ACK) & opts->suboptions) {
> -		u8 len;
> +		u8 len, flag = MPTCP_CAP_HMAC_SHA256;
>
> 		if (OPTION_MPTCP_MPC_SYN & opts->suboptions)
> 			len = TCPOLEN_MPTCP_MPC_SYN;
> @@ -1135,9 +1138,12 @@ void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
> 		else
> 			len = TCPOLEN_MPTCP_MPC_ACK;
>
> +		if (!opts->allow_join_id0)
> +			flag |= MPTCP_CAP_DENY_JOIN_ID0;
> +
> 		*ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len,
> 				      MPTCP_SUPPORTED_VERSION,
> -				      MPTCP_CAP_HMAC_SHA256);
> +				      flag);
>
> 		if (!((OPTION_MPTCP_MPC_SYNACK | OPTION_MPTCP_MPC_ACK) &
> 		    opts->suboptions))
> diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
> index bb901435c2d4..fcbaf47ce3bc 100644
> --- a/net/mptcp/protocol.h
> +++ b/net/mptcp/protocol.h
> @@ -77,8 +77,9 @@
> #define MPTCP_VERSION_MASK	(0x0F)
> #define MPTCP_CAP_CHECKSUM_REQD	BIT(7)
> #define MPTCP_CAP_EXTENSIBILITY	BIT(6)
> +#define MPTCP_CAP_DENY_JOIN_ID0	BIT(5)
> #define MPTCP_CAP_HMAC_SHA256	BIT(0)
> -#define MPTCP_CAP_FLAG_MASK	(0x3F)
> +#define MPTCP_CAP_FLAG_MASK	(0x1F)
>
> /* MPTCP DSS flags */
> #define MPTCP_DSS_DATA_FIN	BIT(4)
> @@ -338,7 +339,8 @@ struct mptcp_subflow_request_sock {
> 	struct	tcp_request_sock sk;
> 	u16	mp_capable : 1,
> 		mp_join : 1,
> -		backup : 1;
> +		backup : 1,
> +		allow_join_id0 : 1;
> 	u8	local_id;
> 	u8	remote_id;
> 	u64	local_key;
> diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
> index 15620bafc544..fb5b6eb5bec9 100644
> --- a/net/mptcp/subflow.c
> +++ b/net/mptcp/subflow.c
> @@ -108,6 +108,7 @@ static void subflow_init_req(struct request_sock *req, const struct sock *sk_lis
>
> 	subflow_req->mp_capable = 0;
> 	subflow_req->mp_join = 0;
> +	subflow_req->allow_join_id0 = mptcp_is_allow_join_id0(sock_net(sk_listener));
> 	subflow_req->msk = NULL;
> 	mptcp_token_init_request(req);
> }
> -- 
> 2.30.2
>
>
>

--
Mat Martineau
Intel

Re: [MPTCP][PATCH v3 mptcp-next 1/4] mptcp: add sysctl allow_join_initial_addr_port

[Mat Martineau]

On Wed, 28 Apr 2021, Geliang Tang wrote:

> This patch added a new sysctl, named allow_join_initial_addr_port, to
> control whether allow peers to send join requests to the IP address and
> port number used by the initial subflow.
>
> Signed-off-by: Geliang Tang <geliangtang@gmail.com>
> ---
> Documentation/networking/mptcp-sysctl.rst | 13 +++++++++++++
> net/mptcp/ctrl.c                          | 16 ++++++++++++++++
> net/mptcp/protocol.h                      |  1 +
> 3 files changed, 30 insertions(+)
>
> diff --git a/Documentation/networking/mptcp-sysctl.rst b/Documentation/networking/mptcp-sysctl.rst
> index 3b352e5f6300..6c67ea3d0b7f 100644
> --- a/Documentation/networking/mptcp-sysctl.rst
> +++ b/Documentation/networking/mptcp-sysctl.rst
> @@ -24,3 +24,16 @@ add_addr_timeout - INTEGER (seconds)
> 	sysctl.
>
> 	Default: 120
> +
> +allow_join_initial_addr_port - INTEGER
> +	Allow peers to send join requests to the IP address and port number used
> +	by the initial subflow if the value is 1. This controls a flag that is
> +	sent to the peer at connection time, and whether such join requests are
> +	accepted or denied.
> +
> +	Joins to addresses advertised with ADD_ADDR are not affected by this
> +	value.
> +
> +	This is a per-namespace sysctl.
> +
> +	Default: 1
> diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
> index 08c152199b89..5c520fcdf93d 100644
> --- a/net/mptcp/ctrl.c
> +++ b/net/mptcp/ctrl.c
> @@ -19,6 +19,7 @@ struct mptcp_pernet {
>
> 	u8 mptcp_enabled;
> 	unsigned int add_addr_timeout;
> +	u8 allow_join_initial_addr_port;
> };
>
> static struct mptcp_pernet *mptcp_get_pernet(struct net *net)
> @@ -36,6 +37,11 @@ unsigned int mptcp_get_add_addr_timeout(struct net *net)
> 	return mptcp_get_pernet(net)->add_addr_timeout;
> }
>
> +int mptcp_is_allow_join_id0(struct net *net)

I suggest "mptcp_allow_join_id0(struct net *net)"


Thanks,
Mat

> +{
> +	return mptcp_get_pernet(net)->allow_join_initial_addr_port;
> +}
> +
> static struct ctl_table mptcp_sysctl_table[] = {
> 	{
> 		.procname = "enabled",
> @@ -54,6 +60,14 @@ static struct ctl_table mptcp_sysctl_table[] = {
> 		.mode = 0644,
> 		.proc_handler = proc_dointvec_jiffies,
> 	},
> +	{
> +		.procname = "allow_join_initial_addr_port",
> +		.maxlen = sizeof(u8),
> +		.mode = 0644,
> +		.proc_handler = proc_dou8vec_minmax,
> +		.extra1       = SYSCTL_ZERO,
> +		.extra2       = SYSCTL_ONE
> +	},
> 	{}
> };
>
> @@ -61,6 +75,7 @@ static void mptcp_pernet_set_defaults(struct mptcp_pernet *pernet)
> {
> 	pernet->mptcp_enabled = 1;
> 	pernet->add_addr_timeout = TCP_RTO_MAX;
> +	pernet->allow_join_initial_addr_port = 1;
> }
>
> static int mptcp_pernet_new_table(struct net *net, struct mptcp_pernet *pernet)
> @@ -77,6 +92,7 @@ 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;
> +	table[2].data = &pernet->allow_join_initial_addr_port;
>
> 	hdr = register_net_sysctl(net, MPTCP_SYSCTL_PATH, table);
> 	if (!hdr)
> diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
> index d230a75af631..bb901435c2d4 100644
> --- a/net/mptcp/protocol.h
> +++ b/net/mptcp/protocol.h
> @@ -524,6 +524,7 @@ static inline void mptcp_subflow_delegated_done(struct mptcp_subflow_context *su
>
> int mptcp_is_enabled(struct net *net);
> unsigned int mptcp_get_add_addr_timeout(struct net *net);
> +int mptcp_is_allow_join_id0(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);
> -- 
> 2.30.2
>
>
>

--
Mat Martineau
Intel

Re: [MPTCP][PATCH v3 mptcp-next 3/4] mptcp: add deny_join_id0 in mptcp_options_received

[Mat Martineau]

On Wed, 28 Apr 2021, Geliang Tang wrote:

> This patch added a new flag named deny_join_id0 in struct
> mptcp_options_received. Set it when MP_CAPABLE with the flag
> MPTCP_CAP_DENYJOIN_ID0 is received.
>
> Also add a new flag deny_join_id0 in struct mptcp_pm_data. When the flag
> mp_opt.deny_join_id0 is set, set this pm->deny_join_id0 flag.
>
> In mptcp_pm_create_subflow_or_signal_addr, if the pm->deny_join_id0 flag
> is set, and the remote address id is zero, stop this connection.
>
> Signed-off-by: Geliang Tang <geliangtang@gmail.com>
> ---
> net/mptcp/options.c    | 6 ++++++
> net/mptcp/pm.c         | 1 +
> net/mptcp/pm_netlink.c | 4 +++-
> net/mptcp/protocol.h   | 4 +++-
> net/mptcp/subflow.c    | 2 ++
> 5 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/net/mptcp/options.c b/net/mptcp/options.c
> index 58ea22bf3d3d..4b6c58a13864 100644
> --- a/net/mptcp/options.c
> +++ b/net/mptcp/options.c
> @@ -77,6 +77,9 @@ static void mptcp_parse_option(const struct sk_buff *skb,
> 		if (flags & MPTCP_CAP_CHECKSUM_REQD)
> 			break;
>
> +		if (flags & MPTCP_CAP_DENY_JOIN_ID0)
> +			mp_opt->deny_join_id0 = 1;
> +
> 		mp_opt->mp_capable = 1;
> 		if (opsize >= TCPOLEN_MPTCP_MPC_SYNACK) {
> 			mp_opt->sndr_key = get_unaligned_be64(ptr);
> @@ -342,6 +345,7 @@ void mptcp_get_options(const struct sk_buff *skb,
> 	mp_opt->dss = 0;
> 	mp_opt->mp_prio = 0;
> 	mp_opt->reset = 0;
> +	mp_opt->deny_join_id0 = 0;
>
> 	length = (th->doff * 4) - sizeof(struct tcphdr);
> 	ptr = (const unsigned char *)(th + 1);
> @@ -1012,6 +1016,8 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
> 	}
>
> 	mptcp_get_options(skb, &mp_opt);
> +	if (mp_opt.deny_join_id0)
> +		WRITE_ONCE(msk->pm.deny_join_id0, true);
> 	if (!check_fully_established(msk, sk, subflow, skb, &mp_opt))
> 		return;
>
> diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
> index 9d00fa6d22e9..d79f015af525 100644
> --- a/net/mptcp/pm.c
> +++ b/net/mptcp/pm.c
> @@ -320,6 +320,7 @@ void mptcp_pm_data_init(struct mptcp_sock *msk)
> 	WRITE_ONCE(msk->pm.addr_signal, 0);
> 	WRITE_ONCE(msk->pm.accept_addr, false);
> 	WRITE_ONCE(msk->pm.accept_subflow, false);
> +	WRITE_ONCE(msk->pm.deny_join_id0, false);
> 	msk->pm.status = 0;
>
> 	spin_lock_init(&msk->pm.lock);
> diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
> index d094588afad8..1491a759a04a 100644
> --- a/net/mptcp/pm_netlink.c
> +++ b/net/mptcp/pm_netlink.c
> @@ -456,10 +456,12 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
> 		if (local) {
> 			struct mptcp_addr_info remote = { 0 };
>
> +			remote_address((struct sock_common *)sk, &remote);
> +			if (!remote.id && READ_ONCE(msk->pm.deny_join_id0))
> +				return;
> 			msk->pm.local_addr_used++;
> 			msk->pm.subflows++;
> 			check_work_pending(msk);
> -			remote_address((struct sock_common *)sk, &remote);
> 			spin_unlock_bh(&msk->pm.lock);
> 			__mptcp_subflow_connect(sk, &local->addr, &remote,
> 						local->flags, local->ifindex);
> diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
> index fcbaf47ce3bc..baf21c53fb42 100644
> --- a/net/mptcp/protocol.h
> +++ b/net/mptcp/protocol.h
> @@ -134,7 +134,8 @@ struct mptcp_options_received {
> 		rm_addr : 1,
> 		mp_prio : 1,
> 		echo : 1,
> -		backup : 1;
> +		backup : 1,
> +		deny_join_id0 : 1;
> 	u32	token;
> 	u32	nonce;
> 	u64	thmac;
> @@ -189,6 +190,7 @@ struct mptcp_pm_data {
> 	bool		work_pending;
> 	bool		accept_addr;
> 	bool		accept_subflow;
> +	bool		deny_join_id0;

I suggest "remote_deny_join_id0" here to clarify that this means "the peer 
will deny id0 joins" not "this PM will deny id0 joins". The naming in 
mptcp_options_received does not need to change, it is just referring to 
the flag.

> 	u8		add_addr_signaled;
> 	u8		add_addr_accepted;
> 	u8		local_addr_used;
> diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
> index fb5b6eb5bec9..2de3b91d1626 100644
> --- a/net/mptcp/subflow.c
> +++ b/net/mptcp/subflow.c
> @@ -405,6 +405,8 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
> 			goto fallback;
> 		}
>
> +		if (mp_opt.deny_join_id0)
> +			WRITE_ONCE(mptcp_sk(parent)->pm.deny_join_id0, true);
> 		subflow->mp_capable = 1;
> 		subflow->can_ack = 1;
> 		subflow->remote_key = mp_opt.sndr_key;
> -- 
> 2.30.2
>
>
>

--
Mat Martineau
Intel

Re: [MPTCP][PATCH v3 mptcp-next 4/4] selftests: mptcp: add deny_join_id0 testcases

[Mat Martineau]

On Wed, 28 Apr 2021, Geliang Tang wrote:

> This patch added a new argument '-d' for mptcp_join.sh script, to invoke
> the testcases for the MP_CAPABLE 'C' flag.
>
> Signed-off-by: Geliang Tang <geliangtang@gmail.com>
> ---
> .../testing/selftests/net/mptcp/mptcp_join.sh | 55 ++++++++++++++++++-
> 1 file changed, 54 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
> index fd99485cf2a4..feabc3ab88eb 100755
> --- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
> +++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
> @@ -124,6 +124,17 @@ reset_with_add_addr_timeout()
> 		-j DROP
> }
>
> +reset_with_allow_join_id0()
> +{
> +	local ns1_enable=$1
> +	local ns2_enable=$2
> +
> +	reset
> +
> +	ip netns exec $ns1 sysctl -q net.mptcp.allow_join_initial_addr_port=$ns1_enable
> +	ip netns exec $ns2 sysctl -q net.mptcp.allow_join_initial_addr_port=$ns2_enable
> +}
> +
> ip -Version > /dev/null 2>&1
> if [ $? -ne 0 ];then
> 	echo "SKIP: Could not run test without ip tool"
> @@ -1374,6 +1385,43 @@ syncookies_tests()
> 	chk_add_nr 1 1
> }
>
> +deny_join_id0_tests()
> +{
> +	# subflow allow join id0 ns1
> +	reset_with_allow_join_id0 1 0
> +	ip netns exec $ns1 ./pm_nl_ctl limits 1 1
> +	ip netns exec $ns2 ./pm_nl_ctl limits 1 1
> +	ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags subflow
> +	run_tests $ns1 $ns2 10.0.1.1
> +	chk_join_nr "single subflow allow join id0 ns1" 1 1 1
> +
> +	# subflow allow join id0 ns2
> +	reset_with_allow_join_id0 0 1
> +	ip netns exec $ns1 ./pm_nl_ctl limits 1 1
> +	ip netns exec $ns2 ./pm_nl_ctl limits 1 1
> +	ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags subflow
> +	run_tests $ns1 $ns2 10.0.1.1
> +	chk_join_nr "single subflow allow join id0 ns2" 0 0 0
> +
> +	# signal address allow join id0 ns1
> +	reset_with_allow_join_id0 1 0
> +	ip netns exec $ns1 ./pm_nl_ctl limits 1 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
> +	chk_join_nr "signal address allow join id0 ns1" 1 1 1
> +	chk_add_nr 1 1
> +
> +	# signal address allow join id0 ns2
> +	reset_with_allow_join_id0 0 1
> +	ip netns exec $ns1 ./pm_nl_ctl limits 1 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
> +	chk_join_nr "signal address allow join id0 ns2" 1 1 1
> +	chk_add_nr 1 1

Could you explain more what the last two tests are intended to check? They 
seem to have the same expected results.

I also experimented with adding a 5th test using 
"reset_with_allow_join_id0 1 1" and that had the same results - the only 
variation was the setting of the 'C' flag in the SYN / SYNACK packets when 
I looked at the pcaps. The different enable settings didn't seem to change 
anything for chk_join_nr or chk_add_nr.


- Mat


> +}
> +
> all_tests()
> {
> 	subflows_tests
> @@ -1387,6 +1435,7 @@ all_tests()
> 	backup_tests
> 	add_addr_ports_tests
> 	syncookies_tests
> +	deny_join_id0_tests
> }
>
> usage()
> @@ -1403,6 +1452,7 @@ usage()
> 	echo "  -b backup_tests"
> 	echo "  -p add_addr_ports_tests"
> 	echo "  -k syncookies_tests"
> +	echo "  -d deny_join_id0_tests"
> 	echo "  -c capture pcap files"
> 	echo "  -h help"
> }
> @@ -1434,7 +1484,7 @@ if [ $do_all_tests -eq 1 ]; then
> 	exit $ret
> fi
>
> -while getopts 'fsltra64bpkch' opt; do
> +while getopts 'fsltra64bpkdch' opt; do
> 	case $opt in
> 		f)
> 			subflows_tests
> @@ -1469,6 +1519,9 @@ while getopts 'fsltra64bpkch' opt; do
> 		k)
> 			syncookies_tests
> 			;;
> +		d)
> +			deny_join_id0_tests
> +			;;
> 		c)
> 			;;
> 		h | *)
> -- 
> 2.30.2
>
>
>

--
Mat Martineau
Intel