[PATCH net-next 0/4] mptcp: cleanup and support more ephemeral ports sockopts

[PATCH net-next 0/4] mptcp: cleanup and support more ephemeral ports sockopts

[Matthieu Baerts]

Patch 1 is a cleanup one: mptcp_is_tcpsk() helper was modifying sock_ops
in some cases which is unexpected with that name.

Patch 2 to 4 add support for two socket options: IP_LOCAL_PORT_RANGE and
IP_BIND_ADDRESS_NO_PORT. The first one is a preparation patch, the
second one adds the support while the last one modifies an existing
selftest to validate the new features.

Signed-off-by: Matthieu Baerts <matttbe@kernel.org>
---
Davide Caratti (1):
      mptcp: don't overwrite sock_ops in mptcp_is_tcpsk()

Maxim Galaganov (3):
      mptcp: rename mptcp_setsockopt_sol_ip_set_transparent()
      mptcp: sockopt: support IP_LOCAL_PORT_RANGE and IP_BIND_ADDRESS_NO_PORT
      selftests/net: add MPTCP coverage for IP_LOCAL_PORT_RANGE

 net/mptcp/protocol.c                              | 108 +++++++++-------------
 net/mptcp/sockopt.c                               |  27 +++++-
 tools/testing/selftests/net/ip_local_port_range.c |  12 +++
 3 files changed, 79 insertions(+), 68 deletions(-)
---
base-commit: 62ed78f3baff396bd928ee77077580c5aa940149
change-id: 20231219-upstream-net-next-20231219-mptcp-sockopts-ephemeral-ports-645522e83161

Best regards,
-- 
Matthieu Baerts <matttbe@kernel.org>

[PATCH net-next 1/4] mptcp: don't overwrite sock_ops in mptcp_is_tcpsk()

[Matthieu Baerts]

From: Davide Caratti <dcaratti@redhat.com>

Eric Dumazet suggests:

 > The fact that mptcp_is_tcpsk() was able to write over sock->ops was a
 > bit strange to me.
 > mptcp_is_tcpsk() should answer a question, with a read-only argument.

re-factor code to avoid overwriting sock_ops inside that function. Also,
change the helper name to reflect the semantics and to disambiguate from
its dual, sk_is_mptcp(). While at it, collapse mptcp_stream_accept() and
mptcp_accept() into a single function, where fallback / non-fallback are
separated into a single sk_is_mptcp() conditional.

Link: https://github.com/multipath-tcp/mptcp_net-next/issues/432
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Matthieu Baerts <matttbe@kernel.org>
---
 net/mptcp/protocol.c | 108 +++++++++++++++++++++------------------------------
 1 file changed, 44 insertions(+), 64 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index bc81ea53a049..5cbbd1221030 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -55,28 +55,14 @@ static u64 mptcp_wnd_end(const struct mptcp_sock *msk)
 	return READ_ONCE(msk->wnd_end);
 }
 
-static bool mptcp_is_tcpsk(struct sock *sk)
+static const struct proto_ops *mptcp_fallback_tcp_ops(const struct sock *sk)
 {
-	struct socket *sock = sk->sk_socket;
-
-	if (unlikely(sk->sk_prot == &tcp_prot)) {
-		/* we are being invoked after mptcp_accept() has
-		 * accepted a non-mp-capable flow: sk is a tcp_sk,
-		 * not an mptcp one.
-		 *
-		 * Hand the socket over to tcp so all further socket ops
-		 * bypass mptcp.
-		 */
-		WRITE_ONCE(sock->ops, &inet_stream_ops);
-		return true;
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
-	} else if (unlikely(sk->sk_prot == &tcpv6_prot)) {
-		WRITE_ONCE(sock->ops, &inet6_stream_ops);
-		return true;
+	if (sk->sk_prot == &tcpv6_prot)
+		return &inet6_stream_ops;
 #endif
-	}
-
-	return false;
+	WARN_ON_ONCE(sk->sk_prot != &tcp_prot);
+	return &inet_stream_ops;
 }
 
 static int __mptcp_socket_create(struct mptcp_sock *msk)
@@ -3258,44 +3244,6 @@ void mptcp_rcv_space_init(struct mptcp_sock *msk, const struct sock *ssk)
 	WRITE_ONCE(msk->wnd_end, msk->snd_nxt + tcp_sk(ssk)->snd_wnd);
 }
 
-static struct sock *mptcp_accept(struct sock *ssk, int flags, int *err,
-				 bool kern)
-{
-	struct sock *newsk;
-
-	pr_debug("ssk=%p, listener=%p", ssk, mptcp_subflow_ctx(ssk));
-	newsk = inet_csk_accept(ssk, flags, err, kern);
-	if (!newsk)
-		return NULL;
-
-	pr_debug("newsk=%p, subflow is mptcp=%d", newsk, sk_is_mptcp(newsk));
-	if (sk_is_mptcp(newsk)) {
-		struct mptcp_subflow_context *subflow;
-		struct sock *new_mptcp_sock;
-
-		subflow = mptcp_subflow_ctx(newsk);
-		new_mptcp_sock = subflow->conn;
-
-		/* is_mptcp should be false if subflow->conn is missing, see
-		 * subflow_syn_recv_sock()
-		 */
-		if (WARN_ON_ONCE(!new_mptcp_sock)) {
-			tcp_sk(newsk)->is_mptcp = 0;
-			goto out;
-		}
-
-		newsk = new_mptcp_sock;
-		MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPCAPABLEPASSIVEACK);
-	} else {
-		MPTCP_INC_STATS(sock_net(ssk),
-				MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK);
-	}
-
-out:
-	newsk->sk_kern_sock = kern;
-	return newsk;
-}
-
 void mptcp_destroy_common(struct mptcp_sock *msk, unsigned int flags)
 {
 	struct mptcp_subflow_context *subflow, *tmp;
@@ -3739,7 +3687,6 @@ static struct proto mptcp_prot = {
 	.connect	= mptcp_connect,
 	.disconnect	= mptcp_disconnect,
 	.close		= mptcp_close,
-	.accept		= mptcp_accept,
 	.setsockopt	= mptcp_setsockopt,
 	.getsockopt	= mptcp_getsockopt,
 	.shutdown	= mptcp_shutdown,
@@ -3849,18 +3796,36 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
 	if (!ssk)
 		return -EINVAL;
 
-	newsk = mptcp_accept(ssk, flags, &err, kern);
+	pr_debug("ssk=%p, listener=%p", ssk, mptcp_subflow_ctx(ssk));
+	newsk = inet_csk_accept(ssk, flags, &err, kern);
 	if (!newsk)
 		return err;
 
-	lock_sock(newsk);
-
-	__inet_accept(sock, newsock, newsk);
-	if (!mptcp_is_tcpsk(newsock->sk)) {
-		struct mptcp_sock *msk = mptcp_sk(newsk);
+	pr_debug("newsk=%p, subflow is mptcp=%d", newsk, sk_is_mptcp(newsk));
+	if (sk_is_mptcp(newsk)) {
 		struct mptcp_subflow_context *subflow;
+		struct sock *new_mptcp_sock;
+
+		subflow = mptcp_subflow_ctx(newsk);
+		new_mptcp_sock = subflow->conn;
+
+		/* is_mptcp should be false if subflow->conn is missing, see
+		 * subflow_syn_recv_sock()
+		 */
+		if (WARN_ON_ONCE(!new_mptcp_sock)) {
+			tcp_sk(newsk)->is_mptcp = 0;
+			goto tcpfallback;
+		}
+
+		newsk = new_mptcp_sock;
+		MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPCAPABLEPASSIVEACK);
+
+		newsk->sk_kern_sock = kern;
+		lock_sock(newsk);
+		__inet_accept(sock, newsock, newsk);
 
 		set_bit(SOCK_CUSTOM_SOCKOPT, &newsock->flags);
+		msk = mptcp_sk(newsk);
 		msk->in_accept_queue = 0;
 
 		/* set ssk->sk_socket of accept()ed flows to mptcp socket.
@@ -3882,6 +3847,21 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
 			if (unlikely(list_is_singular(&msk->conn_list)))
 				inet_sk_state_store(newsk, TCP_CLOSE);
 		}
+	} else {
+		MPTCP_INC_STATS(sock_net(ssk),
+				MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK);
+tcpfallback:
+		newsk->sk_kern_sock = kern;
+		lock_sock(newsk);
+		__inet_accept(sock, newsock, newsk);
+		/* we are being invoked after accepting a non-mp-capable
+		 * flow: sk is a tcp_sk, not an mptcp one.
+		 *
+		 * Hand the socket over to tcp so all further socket ops
+		 * bypass mptcp.
+		 */
+		WRITE_ONCE(newsock->sk->sk_socket->ops,
+			   mptcp_fallback_tcp_ops(newsock->sk));
 	}
 	release_sock(newsk);
 

-- 
2.40.1

[PATCH net-next 2/4] mptcp: rename mptcp_setsockopt_sol_ip_set_transparent()

[Matthieu Baerts]

From: Maxim Galaganov <max@internet.ru>

Next patch extends this function so that it's not specific to
IP_TRANSPARENT. Change function name to mptcp_setsockopt_sol_ip_set().

Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Maxim Galaganov <max@internet.ru>
Signed-off-by: Matthieu Baerts <matttbe@kernel.org>
---
 net/mptcp/sockopt.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index cabe856b2a45..a4bf337e6f77 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -683,8 +683,8 @@ static int mptcp_setsockopt_sol_tcp_nodelay(struct mptcp_sock *msk, sockptr_t op
 	return 0;
 }
 
-static int mptcp_setsockopt_sol_ip_set_transparent(struct mptcp_sock *msk, int optname,
-						   sockptr_t optval, unsigned int optlen)
+static int mptcp_setsockopt_sol_ip_set(struct mptcp_sock *msk, int optname,
+				       sockptr_t optval, unsigned int optlen)
 {
 	struct sock *sk = (struct sock *)msk;
 	struct sock *ssk;
@@ -755,7 +755,7 @@ static int mptcp_setsockopt_v4(struct mptcp_sock *msk, int optname,
 	switch (optname) {
 	case IP_FREEBIND:
 	case IP_TRANSPARENT:
-		return mptcp_setsockopt_sol_ip_set_transparent(msk, optname, optval, optlen);
+		return mptcp_setsockopt_sol_ip_set(msk, optname, optval, optlen);
 	case IP_TOS:
 		return mptcp_setsockopt_v4_set_tos(msk, optname, optval, optlen);
 	}

-- 
2.40.1

[PATCH net-next 3/4] mptcp: sockopt: support IP_LOCAL_PORT_RANGE and IP_BIND_ADDRESS_NO_PORT

[Matthieu Baerts]

From: Maxim Galaganov <max@internet.ru>

Support for IP_BIND_ADDRESS_NO_PORT sockopt was introduced in [1].
Recently [2] allowed its value to be accessed without locking the
socket.

Support for (newer) IP_LOCAL_PORT_RANGE sockopt was introduced in [3].
In the same series a selftest was added in [4]. This selftest also
covers the IP_BIND_ADDRESS_NO_PORT sockopt.

This patch enables getsockopt()/setsockopt() on MPTCP sockets for these
socket options, syncing set values to subflows in sync_socket_options().
Ephemeral port range is synced to subflows, enabling NAT usecase
described in [3].

[1] commit 90c337da1524 ("inet: add IP_BIND_ADDRESS_NO_PORT to overcome
bind(0) limitations")
[2] commit ca571e2eb7eb ("inet: move inet->bind_address_no_port to
inet->inet_flags")
[3] commit 91d0b78c5177 ("inet: Add IP_LOCAL_PORT_RANGE socket option")
[4] commit ae5439658cce ("selftests/net: Cover the IP_LOCAL_PORT_RANGE
socket option")

Signed-off-by: Maxim Galaganov <max@internet.ru>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts <matttbe@kernel.org>
---
 net/mptcp/sockopt.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index a4bf337e6f77..c40f1428e602 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -440,6 +440,8 @@ static bool mptcp_supported_sockopt(int level, int optname)
 		/* should work fine */
 		case IP_FREEBIND:
 		case IP_TRANSPARENT:
+		case IP_BIND_ADDRESS_NO_PORT:
+		case IP_LOCAL_PORT_RANGE:
 
 		/* the following are control cmsg related */
 		case IP_PKTINFO:
@@ -455,7 +457,6 @@ static bool mptcp_supported_sockopt(int level, int optname)
 		/* common stuff that need some love */
 		case IP_TOS:
 		case IP_TTL:
-		case IP_BIND_ADDRESS_NO_PORT:
 		case IP_MTU_DISCOVER:
 		case IP_RECVERR:
 
@@ -710,6 +711,14 @@ static int mptcp_setsockopt_sol_ip_set(struct mptcp_sock *msk, int optname,
 		inet_assign_bit(TRANSPARENT, ssk,
 				inet_test_bit(TRANSPARENT, sk));
 		break;
+	case IP_BIND_ADDRESS_NO_PORT:
+		inet_assign_bit(BIND_ADDRESS_NO_PORT, ssk,
+				inet_test_bit(BIND_ADDRESS_NO_PORT, sk));
+		break;
+	case IP_LOCAL_PORT_RANGE:
+		WRITE_ONCE(inet_sk(ssk)->local_port_range,
+			   READ_ONCE(inet_sk(sk)->local_port_range));
+		break;
 	default:
 		release_sock(sk);
 		WARN_ON_ONCE(1);
@@ -755,6 +764,8 @@ static int mptcp_setsockopt_v4(struct mptcp_sock *msk, int optname,
 	switch (optname) {
 	case IP_FREEBIND:
 	case IP_TRANSPARENT:
+	case IP_BIND_ADDRESS_NO_PORT:
+	case IP_LOCAL_PORT_RANGE:
 		return mptcp_setsockopt_sol_ip_set(msk, optname, optval, optlen);
 	case IP_TOS:
 		return mptcp_setsockopt_v4_set_tos(msk, optname, optval, optlen);
@@ -1350,6 +1361,12 @@ static int mptcp_getsockopt_v4(struct mptcp_sock *msk, int optname,
 	switch (optname) {
 	case IP_TOS:
 		return mptcp_put_int_option(msk, optval, optlen, READ_ONCE(inet_sk(sk)->tos));
+	case IP_BIND_ADDRESS_NO_PORT:
+		return mptcp_put_int_option(msk, optval, optlen,
+				inet_test_bit(BIND_ADDRESS_NO_PORT, sk));
+	case IP_LOCAL_PORT_RANGE:
+		return mptcp_put_int_option(msk, optval, optlen,
+				READ_ONCE(inet_sk(sk)->local_port_range));
 	}
 
 	return -EOPNOTSUPP;
@@ -1450,6 +1467,8 @@ static void sync_socket_options(struct mptcp_sock *msk, struct sock *ssk)
 
 	inet_assign_bit(TRANSPARENT, ssk, inet_test_bit(TRANSPARENT, sk));
 	inet_assign_bit(FREEBIND, ssk, inet_test_bit(FREEBIND, sk));
+	inet_assign_bit(BIND_ADDRESS_NO_PORT, ssk, inet_test_bit(BIND_ADDRESS_NO_PORT, sk));
+	WRITE_ONCE(inet_sk(ssk)->local_port_range, READ_ONCE(inet_sk(sk)->local_port_range));
 }
 
 void mptcp_sockopt_sync_locked(struct mptcp_sock *msk, struct sock *ssk)

-- 
2.40.1

[PATCH net-next 4/4] selftests/net: add MPTCP coverage for IP_LOCAL_PORT_RANGE

[Matthieu Baerts]

From: Maxim Galaganov <max@internet.ru>

Since previous commit, MPTCP has support for IP_BIND_ADDRESS_NO_PORT and
IP_LOCAL_PORT_RANGE sockopts.

Add ip4_mptcp and ip6_mptcp fixture variants to ip_local_port_range
selftest to provide selftest coverage for these sockopts.

Acked-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Maxim Galaganov <max@internet.ru>
Signed-off-by: Matthieu Baerts <matttbe@kernel.org>
---
 tools/testing/selftests/net/ip_local_port_range.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/tools/testing/selftests/net/ip_local_port_range.c b/tools/testing/selftests/net/ip_local_port_range.c
index 75e3fdacdf73..0f217a1cc837 100644
--- a/tools/testing/selftests/net/ip_local_port_range.c
+++ b/tools/testing/selftests/net/ip_local_port_range.c
@@ -146,6 +146,12 @@ FIXTURE_VARIANT_ADD(ip_local_port_range, ip4_stcp) {
 	.so_protocol	= IPPROTO_SCTP,
 };
 
+FIXTURE_VARIANT_ADD(ip_local_port_range, ip4_mptcp) {
+	.so_domain	= AF_INET,
+	.so_type	= SOCK_STREAM,
+	.so_protocol	= IPPROTO_MPTCP,
+};
+
 FIXTURE_VARIANT_ADD(ip_local_port_range, ip6_tcp) {
 	.so_domain	= AF_INET6,
 	.so_type	= SOCK_STREAM,
@@ -164,6 +170,12 @@ FIXTURE_VARIANT_ADD(ip_local_port_range, ip6_stcp) {
 	.so_protocol	= IPPROTO_SCTP,
 };
 
+FIXTURE_VARIANT_ADD(ip_local_port_range, ip6_mptcp) {
+	.so_domain	= AF_INET6,
+	.so_type	= SOCK_STREAM,
+	.so_protocol	= IPPROTO_MPTCP,
+};
+
 TEST_F(ip_local_port_range, invalid_option_value)
 {
 	__u16 val16;

-- 
2.40.1

Re: [PATCH net-next 0/4] mptcp: cleanup and support more ephemeral ports sockopts

[patchwork-bot+netdevbpf]

Hello:

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

On Tue, 19 Dec 2023 22:31:03 +0100 you wrote:
> Patch 1 is a cleanup one: mptcp_is_tcpsk() helper was modifying sock_ops
> in some cases which is unexpected with that name.
> 
> Patch 2 to 4 add support for two socket options: IP_LOCAL_PORT_RANGE and
> IP_BIND_ADDRESS_NO_PORT. The first one is a preparation patch, the
> second one adds the support while the last one modifies an existing
> selftest to validate the new features.
> 
> [...]

Here is the summary with links:
  - [net-next,1/4] mptcp: don't overwrite sock_ops in mptcp_is_tcpsk()
    https://git.kernel.org/netdev/net-next/c/8e2b8a9fa512
  - [net-next,2/4] mptcp: rename mptcp_setsockopt_sol_ip_set_transparent()
    https://git.kernel.org/netdev/net-next/c/57d3117ca80f
  - [net-next,3/4] mptcp: sockopt: support IP_LOCAL_PORT_RANGE and IP_BIND_ADDRESS_NO_PORT
    https://git.kernel.org/netdev/net-next/c/c85636a29264
  - [net-next,4/4] selftests/net: add MPTCP coverage for IP_LOCAL_PORT_RANGE
    https://git.kernel.org/netdev/net-next/c/122db5e3634b

You are awesome, thank you!
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