amt: add control plane of amt interface

It adds definitions and control plane code for AMT.
this is very similar to udp tunneling interfaces such as gtp, vxlan, etc.
In the next patch, data plane code will be added.
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

MAINTAINERS

@@ -1020,6 +1020,14 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/iio/light/ams,as73211.yaml
 F:	drivers/iio/light/as73211.c
 
+AMT (Automatic Multicast Tunneling)
+M:	Taehee Yoo <ap420073@gmail.com>
+L:	netdev@vger.kernel.org
+S:	Maintained
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git
+F:	drivers/net/amt.c
+
 ANALOG DEVICES INC AD7192 DRIVER
 M:	Alexandru Tachici <alexandru.tachici@analog.com>
 L:	linux-iio@vger.kernel.org

drivers/net/Kconfig

@@ -291,6 +291,22 @@ config GTP
 	  To compile this drivers as a module, choose M here: the module
 	  will be called gtp.
 
+config AMT
+	tristate "Automatic Multicast Tunneling (AMT)"
+	depends on INET && IP_MULTICAST
+	select NET_UDP_TUNNEL
+	help
+	  This allows one to create AMT(Automatic Multicast Tunneling)
+	  virtual interfaces that provide multicast tunneling.
+	  There are two roles, Gateway, and Relay.
+	  Gateway Encapsulates IGMP/MLD traffic from listeners to the Relay.
+	  Gateway Decapsulates multicast traffic from the Relay to Listeners.
+	  Relay Encapsulates multicast traffic from Sources to Gateway.
+	  Relay Decapsulates IGMP/MLD traffic from Gateway.
+
+	  To compile this drivers as a module, choose M here: the module
+	  will be called amt.
+
 config MACSEC
 	tristate "IEEE 802.1AE MAC-level encryption (MACsec)"
 	select CRYPTO

drivers/net/Makefile

@@ -14,6 +14,7 @@ obj-$(CONFIG_WIREGUARD) += wireguard/
 obj-$(CONFIG_EQUALIZER) += eql.o
 obj-$(CONFIG_IFB) += ifb.o
 obj-$(CONFIG_MACSEC) += macsec.o
+obj-$(CONFIG_AMT) += amt.o
 obj-$(CONFIG_MACVLAN) += macvlan.o
 obj-$(CONFIG_MACVTAP) += macvtap.o
 obj-$(CONFIG_MII) += mii.o

include/net/amt.h

+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (c) 2021 Taehee Yoo <ap420073@gmail.com>
+ */
+#ifndef _NET_AMT_H_
+#define _NET_AMT_H_
+
+#include <linux/siphash.h>
+#include <linux/jhash.h>
+
+enum amt_msg_type {
+	AMT_MSG_DISCOVERY = 1,
+	AMT_MSG_ADVERTISEMENT,
+	AMT_MSG_REQUEST,
+	AMT_MSG_MEMBERSHIP_QUERY,
+	AMT_MSG_MEMBERSHIP_UPDATE,
+	AMT_MSG_MULTICAST_DATA,
+	AMT_MSG_TEARDOWM,
+	__AMT_MSG_MAX,
+};
+
+#define AMT_MSG_MAX (__AMT_MSG_MAX - 1)
+
+enum amt_status {
+	AMT_STATUS_INIT,
+	AMT_STATUS_SENT_DISCOVERY,
+	AMT_STATUS_RECEIVED_DISCOVERY,
+	AMT_STATUS_SENT_ADVERTISEMENT,
+	AMT_STATUS_RECEIVED_ADVERTISEMENT,
+	AMT_STATUS_SENT_REQUEST,
+	AMT_STATUS_RECEIVED_REQUEST,
+	AMT_STATUS_SENT_QUERY,
+	AMT_STATUS_RECEIVED_QUERY,
+	AMT_STATUS_SENT_UPDATE,
+	AMT_STATUS_RECEIVED_UPDATE,
+	__AMT_STATUS_MAX,
+};
+
+#define AMT_STATUS_MAX (__AMT_STATUS_MAX - 1)
+
+struct amt_header_discovery {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	u32	type:4,
+		version:4,
+		reserved:24;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	u32	version:4,
+		type:4,
+		reserved:24;
+#else
+#error  "Please fix <asm/byteorder.h>"
+#endif
+	__be32	nonce;
+} __packed;
+
+struct amt_header_advertisement {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	u32	type:4,
+		version:4,
+		reserved:24;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	u32	version:4,
+		type:4,
+		reserved:24;
+#else
+#error  "Please fix <asm/byteorder.h>"
+#endif
+	__be32	nonce;
+	__be32	ip4;
+} __packed;
+
+struct amt_header_request {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	u32	type:4,
+		version:4,
+		reserved1:7,
+		p:1,
+		reserved2:16;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	u32	version:4,
+		type:4,
+		p:1,
+		reserved1:7,
+		reserved2:16;
+#else
+#error  "Please fix <asm/byteorder.h>"
+#endif
+	__be32	nonce;
+} __packed;
+
+struct amt_header_membership_query {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	u64	type:4,
+		version:4,
+		reserved:6,
+		l:1,
+		g:1,
+		response_mac:48;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	u64	version:4,
+		type:4,
+		g:1,
+		l:1,
+		reserved:6,
+		response_mac:48;
+#else
+#error  "Please fix <asm/byteorder.h>"
+#endif
+	__be32	nonce;
+} __packed;
+
+struct amt_header_membership_update {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	u64	type:4,
+		version:4,
+		reserved:8,
+		response_mac:48;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	u64	version:4,
+		type:4,
+		reserved:8,
+		response_mac:48;
+#else
+#error  "Please fix <asm/byteorder.h>"
+#endif
+	__be32	nonce;
+} __packed;
+
+struct amt_header_mcast_data {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	u16	type:4,
+		version:4,
+		reserved:8;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	u16	version:4,
+		type:4,
+		reserved:8;
+#else
+#error  "Please fix <asm/byteorder.h>"
+#endif
+} __packed;
+
+struct amt_gw_headers {
+	union {
+		struct amt_header_discovery discovery;
+		struct amt_header_request request;
+		struct amt_header_membership_update update;
+	};
+} __packed;
+
+struct amt_relay_headers {
+	union {
+		struct amt_header_advertisement advertisement;
+		struct amt_header_membership_query query;
+		struct amt_header_mcast_data data;
+	};
+} __packed;
+
+struct amt_dev {
+	struct net_device       *dev;
+	struct net_device       *stream_dev;
+	struct net		*net;
+	/* Global lock for amt device */
+	spinlock_t		lock;
+	/* Used only in relay mode */
+	struct list_head        tunnel_list;
+	struct gro_cells	gro_cells;
+
+	/* Protected by RTNL */
+	struct delayed_work     discovery_wq;
+	/* Protected by RTNL */
+	struct delayed_work     req_wq;
+	/* Protected by RTNL */
+	struct delayed_work     secret_wq;
+	/* AMT status */
+	enum amt_status		status;
+	/* Generated key */
+	siphash_key_t		key;
+	struct socket	  __rcu *sock;
+	u32			max_groups;
+	u32			max_sources;
+	u32			hash_buckets;
+	u32			hash_seed;
+	/* Default 128 */
+	u32                     max_tunnels;
+	/* Default 128 */
+	u32                     nr_tunnels;
+	/* Gateway or Relay mode */
+	u32                     mode;
+	/* Default 2268 */
+	__be16			relay_port;
+	/* Default 2268 */
+	__be16			gw_port;
+	/* Outer local ip */
+	__be32			local_ip;
+	/* Outer remote ip */
+	__be32			remote_ip;
+	/* Outer discovery ip */
+	__be32			discovery_ip;
+	/* Only used in gateway mode */
+	__be32			nonce;
+	/* Gateway sent request and received query */
+	bool			ready4;
+	bool			ready6;
+	u8			req_cnt;
+	u8			qi;
+	u64			qrv;
+	u64			qri;
+	/* Used only in gateway mode */
+	u64			mac:48,
+				reserved:16;
+};
+
+#define AMT_MAX_GROUP		32
+#define AMT_MAX_SOURCE		128
+#define AMT_HSIZE_SHIFT		8
+#define AMT_HSIZE		(1 << AMT_HSIZE_SHIFT)
+
+#define AMT_INIT_QUERY_INTERVAL	125
+#define IANA_AMT_UDP_PORT	2268
+#define AMT_MAX_TUNNELS         128
+#define AMT_MAX_REQS		128
+#define AMT_GW_HLEN (sizeof(struct iphdr) + \
+		     sizeof(struct udphdr) + \
+		     sizeof(struct amt_gw_headers))
+#define AMT_RELAY_HLEN (sizeof(struct iphdr) + \
+		     sizeof(struct udphdr) + \
+		     sizeof(struct amt_relay_headers))
+
+static inline bool netif_is_amt(const struct net_device *dev)
+{
+	return dev->rtnl_link_ops && !strcmp(dev->rtnl_link_ops->kind, "amt");
+}
+
+#endif /* _NET_AMT_H_ */

include/uapi/linux/amt.h

+/* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note */
+/*
+ * Copyright (c) 2021 Taehee Yoo <ap420073@gmail.com>
+ */
+#ifndef _UAPI_AMT_H_
+#define _UAPI_AMT_H_
+
+enum ifla_amt_mode {
+	/* AMT interface works as Gateway mode.
+	 * The Gateway mode encapsulates IGMP/MLD traffic and decapsulates
+	 * multicast traffic.
+	 */
+	AMT_MODE_GATEWAY = 0,
+	/* AMT interface works as Relay mode.
+	 * The Relay mode encapsulates multicast traffic and decapsulates
+	 * IGMP/MLD traffic.
+	 */
+	AMT_MODE_RELAY,
+	__AMT_MODE_MAX,
+};
+
+#define AMT_MODE_MAX (__AMT_MODE_MAX - 1)
+
+enum {
+	IFLA_AMT_UNSPEC,
+	/* This attribute specify mode etier Gateway or Relay. */
+	IFLA_AMT_MODE,
+	/* This attribute specify Relay port.
+	 * AMT interface is created as Gateway mode, this attribute is used
+	 * to specify relay(remote) port.
+	 * AMT interface is created as Relay mode, this attribute is used
+	 * as local port.
+	 */
+	IFLA_AMT_RELAY_PORT,
+	/* This attribute specify Gateway port.
+	 * AMT interface is created as Gateway mode, this attribute is used
+	 * as local port.
+	 * AMT interface is created as Relay mode, this attribute is not used.
+	 */
+	IFLA_AMT_GATEWAY_PORT,
+	/* This attribute specify physical device */
+	IFLA_AMT_LINK,
+	/* This attribute specify local ip address */
+	IFLA_AMT_LOCAL_IP,
+	/* This attribute specify Relay ip address.
+	 * So, this is not used by Relay.
+	 */
+	IFLA_AMT_REMOTE_IP,
+	/* This attribute specify Discovery ip address.
+	 * When Gateway get started, it send discovery message to find the
+	 * Relay's ip address.
+	 * So, this is not used by Relay.
+	 */
+	IFLA_AMT_DISCOVERY_IP,
+	/* This attribute specify number of maximum tunnel. */
+	IFLA_AMT_MAX_TUNNELS,
+	__IFLA_AMT_MAX,
+};
+
+#define IFLA_AMT_MAX (__IFLA_AMT_MAX - 1)
+
+#endif /* _UAPI_AMT_H_ */