bridge: cfm: Kernel space implementation of CFM. CCM frame TX added.

This is the second commit of the implementation of the CFM protocol
according to 802.1Q section 12.14.

Functionality is extended with CCM frame transmission.

Interface is extended with these functions:
br_cfm_cc_rdi_set()
br_cfm_cc_ccm_tx()
br_cfm_cc_config_set()

A MEP Continuity Check feature can be configured by
br_cfm_cc_config_set()
The Continuity Check parameters can be configured to be used when
transmitting CCM.

A MEP can be configured to start or stop transmission of CCM frames by
br_cfm_cc_ccm_tx()
The CCM will be transmitted for a selected period in seconds.
Must call this function before timeout to keep transmission alive.

A MEP transmitting CCM can be configured with inserted RDI in PDU by
br_cfm_cc_rdi_set()

Signed-off-by: Henrik Bjoernlund <[e-mail]>
Reviewed-by: Horatiu Vultur <[e-mail]>
Acked-by: Nikolay Aleksandrov <[e-mail]>
Signed-off-by: Jakub Kicinski <[e-mail]>

include/uapi/linux/cfm_bridge.h

···
 #include <linux/types.h>
 #include <linux/if_ether.h>
 
-#define CFM_MAID_LENGTH		48
+#define ETHER_HEADER_LENGTH		(6+6+4+2)
+#define CFM_MAID_LENGTH			48
+#define CFM_CCM_PDU_LENGTH		75
+#define CFM_PORT_STATUS_TLV_LENGTH	4
+#define CFM_IF_STATUS_TLV_LENGTH	4
+#define CFM_IF_STATUS_TLV_TYPE		4
+#define CFM_PORT_STATUS_TLV_TYPE	2
+#define CFM_ENDE_TLV_TYPE		0
+#define CFM_CCM_MAX_FRAME_LENGTH	(ETHER_HEADER_LENGTH+\
+					 CFM_CCM_PDU_LENGTH+\
+					 CFM_PORT_STATUS_TLV_LENGTH+\
+					 CFM_IF_STATUS_TLV_LENGTH)
+#define CFM_FRAME_PRIO			7
+#define CFM_CCM_TLV_OFFSET		70
+#define CFM_CCM_ITU_RESERVED_SIZE	16
+
+struct br_cfm_common_hdr {
+	__u8 mdlevel_version;
+	__u8 opcode;
+	__u8 flags;
+	__u8 tlv_offset;
+};
+
+enum br_cfm_opcodes {
+	BR_CFM_OPCODE_CCM = 0x1,
+};
 
 /* MEP domain */
 enum br_cfm_domain {
···
 enum br_cfm_mep_direction {
 	BR_CFM_MEP_DIRECTION_DOWN,
 	BR_CFM_MEP_DIRECTION_UP,
+};
+
+/* CCM interval supported. */
+enum br_cfm_ccm_interval {
+	BR_CFM_CCM_INTERVAL_NONE,
+	BR_CFM_CCM_INTERVAL_3_3_MS,
+	BR_CFM_CCM_INTERVAL_10_MS,
+	BR_CFM_CCM_INTERVAL_100_MS,
+	BR_CFM_CCM_INTERVAL_1_SEC,
+	BR_CFM_CCM_INTERVAL_10_SEC,
+	BR_CFM_CCM_INTERVAL_1_MIN,
+	BR_CFM_CCM_INTERVAL_10_MIN,
 };
 
 #endif

net/bridge/br_cfm.c

···
 	return NULL;
 }
 
+/* Calculate the CCM interval in us. */
+static u32 interval_to_us(enum br_cfm_ccm_interval interval)
+{
+	switch (interval) {
+	case BR_CFM_CCM_INTERVAL_NONE:
+		return 0;
+	case BR_CFM_CCM_INTERVAL_3_3_MS:
+		return 3300;
+	case BR_CFM_CCM_INTERVAL_10_MS:
+		return 10 * 1000;
+	case BR_CFM_CCM_INTERVAL_100_MS:
+		return 100 * 1000;
+	case BR_CFM_CCM_INTERVAL_1_SEC:
+		return 1000 * 1000;
+	case BR_CFM_CCM_INTERVAL_10_SEC:
+		return 10 * 1000 * 1000;
+	case BR_CFM_CCM_INTERVAL_1_MIN:
+		return 60 * 1000 * 1000;
+	case BR_CFM_CCM_INTERVAL_10_MIN:
+		return 10 * 60 * 1000 * 1000;
+	}
+	return 0;
+}
+
+/* Convert the interface interval to CCM PDU value. */
+static u32 interval_to_pdu(enum br_cfm_ccm_interval interval)
+{
+	switch (interval) {
+	case BR_CFM_CCM_INTERVAL_NONE:
+		return 0;
+	case BR_CFM_CCM_INTERVAL_3_3_MS:
+		return 1;
+	case BR_CFM_CCM_INTERVAL_10_MS:
+		return 2;
+	case BR_CFM_CCM_INTERVAL_100_MS:
+		return 3;
+	case BR_CFM_CCM_INTERVAL_1_SEC:
+		return 4;
+	case BR_CFM_CCM_INTERVAL_10_SEC:
+		return 5;
+	case BR_CFM_CCM_INTERVAL_1_MIN:
+		return 6;
+	case BR_CFM_CCM_INTERVAL_10_MIN:
+		return 7;
+	}
+	return 0;
+}
+
+static struct sk_buff *ccm_frame_build(struct br_cfm_mep *mep,
+				       const struct br_cfm_cc_ccm_tx_info *const tx_info)
+
+{
+	struct br_cfm_common_hdr *common_hdr;
+	struct net_bridge_port *b_port;
+	struct br_cfm_maid *maid;
+	u8 *itu_reserved, *e_tlv;
+	struct ethhdr *eth_hdr;
+	struct sk_buff *skb;
+	__be32 *status_tlv;
+	__be32 *snumber;
+	__be16 *mepid;
+
+	skb = dev_alloc_skb(CFM_CCM_MAX_FRAME_LENGTH);
+	if (!skb)
+		return NULL;
+
+	rcu_read_lock();
+	b_port = rcu_dereference(mep->b_port);
+	if (!b_port) {
+		kfree_skb(skb);
+		rcu_read_unlock();
+		return NULL;
+	}
+	skb->dev = b_port->dev;
+	rcu_read_unlock();
+	/* The device cannot be deleted until the work_queue functions has
+	 * completed. This function is called from ccm_tx_work_expired()
+	 * that is a work_queue functions.
+	 */
+
+	skb->protocol = htons(ETH_P_CFM);
+	skb->priority = CFM_FRAME_PRIO;
+
+	/* Ethernet header */
+	eth_hdr = skb_put(skb, sizeof(*eth_hdr));
+	ether_addr_copy(eth_hdr->h_dest, tx_info->dmac.addr);
+	ether_addr_copy(eth_hdr->h_source, mep->config.unicast_mac.addr);
+	eth_hdr->h_proto = htons(ETH_P_CFM);
+
+	/* Common CFM Header */
+	common_hdr = skb_put(skb, sizeof(*common_hdr));
+	common_hdr->mdlevel_version = mep->config.mdlevel << 5;
+	common_hdr->opcode = BR_CFM_OPCODE_CCM;
+	common_hdr->flags = (mep->rdi << 7) |
+			    interval_to_pdu(mep->cc_config.exp_interval);
+	common_hdr->tlv_offset = CFM_CCM_TLV_OFFSET;
+
+	/* Sequence number */
+	snumber = skb_put(skb, sizeof(*snumber));
+	if (tx_info->seq_no_update) {
+		*snumber = cpu_to_be32(mep->ccm_tx_snumber);
+		mep->ccm_tx_snumber += 1;
+	} else {
+		*snumber = 0;
+	}
+
+	mepid = skb_put(skb, sizeof(*mepid));
+	*mepid = cpu_to_be16((u16)mep->config.mepid);
+
+	maid = skb_put(skb, sizeof(*maid));
+	memcpy(maid->data, mep->cc_config.exp_maid.data, sizeof(maid->data));
+
+	/* ITU reserved (CFM_CCM_ITU_RESERVED_SIZE octets) */
+	itu_reserved = skb_put(skb, CFM_CCM_ITU_RESERVED_SIZE);
+	memset(itu_reserved, 0, CFM_CCM_ITU_RESERVED_SIZE);
+
+	/* Generel CFM TLV format:
+	 * TLV type:		one byte
+	 * TLV value length:	two bytes
+	 * TLV value:		'TLV value length' bytes
+	 */
+
+	/* Port status TLV. The value length is 1. Total of 4 bytes. */
+	if (tx_info->port_tlv) {
+		status_tlv = skb_put(skb, sizeof(*status_tlv));
+		*status_tlv = cpu_to_be32((CFM_PORT_STATUS_TLV_TYPE << 24) |
+					  (1 << 8) |	/* Value length */
+					  (tx_info->port_tlv_value & 0xFF));
+	}
+
+	/* Interface status TLV. The value length is 1. Total of 4 bytes. */
+	if (tx_info->if_tlv) {
+		status_tlv = skb_put(skb, sizeof(*status_tlv));
+		*status_tlv = cpu_to_be32((CFM_IF_STATUS_TLV_TYPE << 24) |
+					  (1 << 8) |	/* Value length */
+					  (tx_info->if_tlv_value & 0xFF));
+	}
+
+	/* End TLV */
+	e_tlv = skb_put(skb, sizeof(*e_tlv));
+	*e_tlv = CFM_ENDE_TLV_TYPE;
+
+	return skb;
+}
+
+static void ccm_frame_tx(struct sk_buff *skb)
+{
+	skb_reset_network_header(skb);
+	dev_queue_xmit(skb);
+}
+
+/* This function is called with the configured CC 'expected_interval'
+ * in order to drive CCM transmission when enabled.
+ */
+static void ccm_tx_work_expired(struct work_struct *work)
+{
+	struct delayed_work *del_work;
+	struct br_cfm_mep *mep;
+	struct sk_buff *skb;
+	u32 interval_us;
+
+	del_work = to_delayed_work(work);
+	mep = container_of(del_work, struct br_cfm_mep, ccm_tx_dwork);
+
+	if (time_before_eq(mep->ccm_tx_end, jiffies)) {
+		/* Transmission period has ended */
+		mep->cc_ccm_tx_info.period = 0;
+		return;
+	}
+
+	skb = ccm_frame_build(mep, &mep->cc_ccm_tx_info);
+	if (skb)
+		ccm_frame_tx(skb);
+
+	interval_us = interval_to_us(mep->cc_config.exp_interval);
+	queue_delayed_work(system_wq, &mep->ccm_tx_dwork,
+			   usecs_to_jiffies(interval_us));
+}
+
 int br_cfm_mep_create(struct net_bridge *br,
 		      const u32 instance,
 		      struct br_cfm_mep_create *const create,
···
 	rcu_assign_pointer(mep->b_port, p);
 
 	INIT_HLIST_HEAD(&mep->peer_mep_list);
+	INIT_DELAYED_WORK(&mep->ccm_tx_dwork, ccm_tx_work_expired);
 
 	hlist_add_tail_rcu(&mep->head, &br->mep_list);
 
···
 		hlist_del_rcu(&peer_mep->head);
 		kfree_rcu(peer_mep, rcu);
 	}
+
+	cancel_delayed_work_sync(&mep->ccm_tx_dwork);
 
 	RCU_INIT_POINTER(mep->b_port, NULL);
 	hlist_del_rcu(&mep->head);
···
 	}
 
 	mep->config = *config;
+
+	return 0;
+}
+
+int br_cfm_cc_config_set(struct net_bridge *br,
+			 const u32 instance,
+			 const struct br_cfm_cc_config *const config,
+			 struct netlink_ext_ack *extack)
+{
+	struct br_cfm_mep *mep;
+
+	ASSERT_RTNL();
+
+	mep = br_mep_find(br, instance);
+	if (!mep) {
+		NL_SET_ERR_MSG_MOD(extack,
+				   "MEP instance does not exists");
+		return -ENOENT;
+	}
+
+	/* Check for no change in configuration */
+	if (memcmp(config, &mep->cc_config, sizeof(*config)) == 0)
+		return 0;
+
+	mep->cc_config = *config;
+	mep->ccm_tx_snumber = 1;
 
 	return 0;
 }
···
 
 	hlist_del_rcu(&peer_mep->head);
 	kfree_rcu(peer_mep, rcu);
+
+	return 0;
+}
+
+int br_cfm_cc_rdi_set(struct net_bridge *br, const u32 instance,
+		      const bool rdi, struct netlink_ext_ack *extack)
+{
+	struct br_cfm_mep *mep;
+
+	ASSERT_RTNL();
+
+	mep = br_mep_find(br, instance);
+	if (!mep) {
+		NL_SET_ERR_MSG_MOD(extack,
+				   "MEP instance does not exists");
+		return -ENOENT;
+	}
+
+	mep->rdi = rdi;
+
+	return 0;
+}
+
+int br_cfm_cc_ccm_tx(struct net_bridge *br, const u32 instance,
+		     const struct br_cfm_cc_ccm_tx_info *const tx_info,
+		     struct netlink_ext_ack *extack)
+{
+	struct br_cfm_mep *mep;
+
+	ASSERT_RTNL();
+
+	mep = br_mep_find(br, instance);
+	if (!mep) {
+		NL_SET_ERR_MSG_MOD(extack,
+				   "MEP instance does not exists");
+		return -ENOENT;
+	}
+
+	if (memcmp(tx_info, &mep->cc_ccm_tx_info, sizeof(*tx_info)) == 0) {
+		/* No change in tx_info. */
+		if (mep->cc_ccm_tx_info.period == 0)
+			/* Transmission is not enabled - just return */
+			return 0;
+
+		/* Transmission is ongoing, the end time is recalculated */
+		mep->ccm_tx_end = jiffies +
+				  usecs_to_jiffies(tx_info->period * 1000000);
+		return 0;
+	}
+
+	if (tx_info->period == 0 && mep->cc_ccm_tx_info.period == 0)
+		/* Some change in info and transmission is not ongoing */
+		goto save;
+
+	if (tx_info->period != 0 && mep->cc_ccm_tx_info.period != 0) {
+		/* Some change in info and transmission is ongoing
+		 * The end time is recalculated
+		 */
+		mep->ccm_tx_end = jiffies +
+				  usecs_to_jiffies(tx_info->period * 1000000);
+
+		goto save;
+	}
+
+	if (tx_info->period == 0 && mep->cc_ccm_tx_info.period != 0) {
+		cancel_delayed_work_sync(&mep->ccm_tx_dwork);
+		goto save;
+	}
+
+	/* Start delayed work to transmit CCM frames. It is done with zero delay
+	 * to send first frame immediately
+	 */
+	mep->ccm_tx_end = jiffies + usecs_to_jiffies(tx_info->period * 1000000);
+	queue_delayed_work(system_wq, &mep->ccm_tx_dwork, 0);
+
+save:
+	mep->cc_ccm_tx_info = *tx_info;
 
 	return 0;
 }

net/bridge/br_private_cfm.h

···
 			  const struct br_cfm_mep_config *const config,
 			  struct netlink_ext_ack *extack);
 
+struct br_cfm_maid {
+	u8 data[CFM_MAID_LENGTH];
+};
+
+struct br_cfm_cc_config {
+	/* Expected received CCM PDU MAID. */
+	struct br_cfm_maid exp_maid;
+
+	/* Expected received CCM PDU interval. */
+	/* Transmitting CCM PDU interval when CCM tx is enabled. */
+	enum br_cfm_ccm_interval exp_interval;
+};
+
+int br_cfm_cc_config_set(struct net_bridge *br,
+			 const u32 instance,
+			 const struct br_cfm_cc_config *const config,
+			 struct netlink_ext_ack *extack);
+
 int br_cfm_cc_peer_mep_add(struct net_bridge *br, const u32 instance,
 			   u32 peer_mep_id,
 			   struct netlink_ext_ack *extack);
···
 			      u32 peer_mep_id,
 			      struct netlink_ext_ack *extack);
 
+/* Transmitted CCM Remote Defect Indication status set.
+ * This RDI is inserted in transmitted CCM PDUs if CCM transmission is enabled.
+ * See br_cfm_cc_ccm_tx() with interval != BR_CFM_CCM_INTERVAL_NONE
+ */
+int br_cfm_cc_rdi_set(struct net_bridge *br, const u32 instance,
+		      const bool rdi, struct netlink_ext_ack *extack);
+
+/* OAM PDU Tx information */
+struct br_cfm_cc_ccm_tx_info {
+	struct mac_addr dmac;
+	/* The CCM will be transmitted for this period in seconds.
+	 * Call br_cfm_cc_ccm_tx before timeout to keep transmission alive.
+	 * When period is zero any ongoing transmission will be stopped.
+	 */
+	u32 period;
+
+	bool seq_no_update; /* Update Tx CCM sequence number */
+	bool if_tlv; /* Insert Interface Status TLV */
+	u8 if_tlv_value; /* Interface Status TLV value */
+	bool port_tlv; /* Insert Port Status TLV */
+	u8 port_tlv_value; /* Port Status TLV value */
+	/* Sender ID TLV ??
+	 * Organization-Specific TLV ??
+	 */
+};
+
+int br_cfm_cc_ccm_tx(struct net_bridge *br, const u32 instance,
+		     const struct br_cfm_cc_ccm_tx_info *const tx_info,
+		     struct netlink_ext_ack *extack);
+
 struct br_cfm_mep {
 	/* list header of MEP instances */
 	struct hlist_node		head;
 	u32				instance;
 	struct br_cfm_mep_create	create;
 	struct br_cfm_mep_config	config;
+	struct br_cfm_cc_config		cc_config;
+	struct br_cfm_cc_ccm_tx_info	cc_ccm_tx_info;
 	/* List of multiple peer MEPs */
 	struct hlist_head		peer_mep_list;
 	struct net_bridge_port __rcu	*b_port;
+	unsigned long			ccm_tx_end;
+	struct delayed_work		ccm_tx_dwork;
+	u32				ccm_tx_snumber;
+	bool				rdi;
 	struct rcu_head			rcu;
 };