[PATCH net-next 2/4] net: hsr: emit RedBox-MAC TLV in PRP RedBox supervision frames

[Xin Xie <xiexinet@gmail.com>]

A PRP RedBox must announce the SANs it proxies so peers populate their
proxy node tables. The proxy-announce machinery (hsr_proxy_announce(),
armed via hsr->redbox) already iterates proxy_node_db under RCU and calls
send_sv_frame() once per SAN, but the PRP sender emitted neither the
announced SAN MAC nor the RedBox-MAC TLV that IEC 62439-3 requires.

Extend send_prp_supervision_frame() so that, for a proxy-announce
(identified by the interlink port, an O(1) test), the frame carries the
proxied SAN MAC as MacAddressA followed by the RedBox-MAC TLV (Type 30)
and an explicit End-of-TLV marker before padding.

hsr_get_node() must also accept the reinjected proxy-announce: a PRP
supervision frame is an untagged ETH_P_PRP frame (mac_len == ETH_HLEN, the
RCT is appended only on egress) sourced from macaddress_redbox, which is
never learned from data. Exempt only PRP supervision frames from the
hsr_ethhdr length guard; HSR (ETH_P_HSR) supervision is front-tagged and
keeps the original guard, so HSR malformed-frame filtering is unchanged.

Signed-off-by: Xin Xie <xiexinet@gmail.com>
---
 net/hsr/hsr_device.c   | 33 ++++++++++++++++++++++++++++++---
 net/hsr/hsr_framereg.c | 13 +++++++++++--
 2 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/net/hsr/hsr_device.c b/net/hsr/hsr_device.c
index 5555b71ab..7cc21253c 100644
--- a/net/hsr/hsr_device.c
+++ b/net/hsr/hsr_device.c
@@ -372,10 +372,21 @@ static void send_prp_supervision_frame(struct hsr_port *master,
 {
 	struct hsr_priv *hsr = master->hsr;
 	struct hsr_sup_payload *hsr_sp;
+	struct hsr_sup_tlv *hsr_stlv;
 	struct hsr_sup_tag *hsr_stag;
 	struct sk_buff *skb;
+	bool redbox_proxy;
+	int extra = 0;
+
+	redbox_proxy = hsr->redbox && master->type == HSR_PT_INTERLINK;
+
+	/* A proxy-announce carries a RedBox-MAC TLV and an EOT marker. */
+	if (redbox_proxy)
+		extra = sizeof(struct hsr_sup_tlv) +
+			sizeof(struct hsr_sup_payload) +
+			sizeof(struct hsr_sup_tlv);
 
-	skb = hsr_init_skb(master, 0);
+	skb = hsr_init_skb(master, extra);
 	if (!skb) {
 		netdev_warn_once(master->dev, "PRP: Could not send supervision frame\n");
 		return;
@@ -393,9 +404,25 @@ static void send_prp_supervision_frame(struct hsr_port *master,
 	hsr_stag->tlv.HSR_TLV_type = PRP_TLV_LIFE_CHECK_DD;
 	hsr_stag->tlv.HSR_TLV_length = sizeof(struct hsr_sup_payload);
 
-	/* Payload: MacAddressA */
+	/* Payload: MacAddressA, the announced node. */
 	hsr_sp = skb_put(skb, sizeof(struct hsr_sup_payload));
-	ether_addr_copy(hsr_sp->macaddress_A, master->dev->dev_addr);
+	ether_addr_copy(hsr_sp->macaddress_A, addr);
+
+	/* Proxy-announce: append the RedBox-MAC TLV (Type 30) and an explicit
+	 * EOT to terminate the TLV chain before zero padding.
+	 */
+	if (redbox_proxy) {
+		hsr_stlv = skb_put(skb, sizeof(struct hsr_sup_tlv));
+		hsr_stlv->HSR_TLV_type = PRP_TLV_REDBOX_MAC;
+		hsr_stlv->HSR_TLV_length = sizeof(struct hsr_sup_payload);
+
+		hsr_sp = skb_put(skb, sizeof(struct hsr_sup_payload));
+		ether_addr_copy(hsr_sp->macaddress_A, hsr->macaddress_redbox);
+
+		hsr_stlv = skb_put(skb, sizeof(struct hsr_sup_tlv));
+		hsr_stlv->HSR_TLV_type = HSR_TLV_EOT;
+		hsr_stlv->HSR_TLV_length = 0;
+	}
 
 	if (skb_put_padto(skb, ETH_ZLEN)) {
 		spin_unlock_bh(&hsr->seqnr_lock);
diff --git a/net/hsr/hsr_framereg.c b/net/hsr/hsr_framereg.c
index 7a7c52a95..37ade2dde 100644
--- a/net/hsr/hsr_framereg.c
+++ b/net/hsr/hsr_framereg.c
@@ -293,8 +293,17 @@ struct hsr_node *hsr_get_node(struct hsr_port *port, struct list_head *node_db,
 	 */
 	if (ethhdr->h_proto == htons(ETH_P_PRP) ||
 	    ethhdr->h_proto == htons(ETH_P_HSR)) {
-		/* Check if skb contains hsr_ethhdr */
-		if (skb->mac_len < sizeof(struct hsr_ethhdr))
+		bool prp_sup;
+
+		/* A PRP supervision frame is an untagged ETH_P_PRP frame
+		 * (mac_len == ETH_HLEN); its RCT is appended only on egress.
+		 * HSR (ETH_P_HSR) supervision is front-tagged and still must
+		 * contain a struct hsr_ethhdr.
+		 */
+		prp_sup = hsr->prot_version == PRP_V1 &&
+			  ethhdr->h_proto == htons(ETH_P_PRP) && is_sup;
+
+		if (!prp_sup && skb->mac_len < sizeof(struct hsr_ethhdr))
 			return NULL;
 	} else {
 		rct = skb_get_PRP_rct(skb);
-- 
2.53.0