// SPDX-License-Identifier: GPL-2.0
/* Copyright 2011-2014 Autronica Fire and Security AS
 *
 * Author(s):
 *      2011-2014 Arvid Brodin, arvid.brodin@alten.se
 *
 * Frame router for HSR and PRP.
 */

#include "hsr_forward.h"
#include <linux/types.h>
#include <linux/skbuff.h>
#include <linux/etherdevice.h>
#include <linux/if_vlan.h>
#include "hsr_main.h"
#include "hsr_framereg.h"

struct hsr_node;

/* The uses I can see for these HSR supervision frames are:
 * 1) Use the frames that are sent after node initialization ("HSR_TLV.Type =
 *    22") to reset any sequence_nr counters belonging to that node. Useful if
 *    the other node's counter has been reset for some reason.
 *    --
 *    Or not - resetting the counter and bridging the frame would create a
 *    loop, unfortunately.
 *
 * 2) Use the LifeCheck frames to detect ring breaks. I.e. if no LifeCheck
 *    frame is received from a particular node, we know something is wrong.
 *    We just register these (as with normal frames) and throw them away.
 *
 * 3) Allow different MAC addresses for the two slave interfaces, using the
 *    MacAddressA field.
 */
static bool is_supervision_frame(struct hsr_priv *hsr, struct sk_buff *skb)
{
        struct ethhdr *eth_hdr;
        struct hsr_sup_tag *hsr_sup_tag;
        struct hsrv1_ethhdr_sp *hsr_V1_hdr;
        struct hsr_sup_tlv *hsr_sup_tlv;
        u16 total_length = 0;

        WARN_ON_ONCE(!skb_mac_header_was_set(skb));
        eth_hdr = (struct ethhdr *)skb_mac_header(skb);

        /* Correct addr? */
        if (!ether_addr_equal(eth_hdr->h_dest,
                              hsr->sup_multicast_addr))
                return false;

        /* Correct ether type?. */
        if (!(eth_hdr->h_proto == htons(ETH_P_PRP) ||
              eth_hdr->h_proto == htons(ETH_P_HSR)))
                return false;

        /* Get the supervision header from correct location. */
        if (eth_hdr->h_proto == htons(ETH_P_HSR)) { /* Okay HSRv1. */
                total_length = sizeof(struct hsrv1_ethhdr_sp);
                if (!pskb_may_pull(skb, total_length))
                        return false;

                hsr_V1_hdr = (struct hsrv1_ethhdr_sp *)skb_mac_header(skb);
                if (hsr_V1_hdr->hsr.encap_proto != htons(ETH_P_PRP))
                        return false;

                hsr_sup_tag = &hsr_V1_hdr->hsr_sup;
        } else {
                total_length = sizeof(struct hsrv0_ethhdr_sp);
                if (!pskb_may_pull(skb, total_length))
                        return false;

                hsr_sup_tag =
                     &((struct hsrv0_ethhdr_sp *)skb_mac_header(skb))->hsr_sup;
        }

        if (hsr_sup_tag->tlv.HSR_TLV_type != HSR_TLV_ANNOUNCE &&
            hsr_sup_tag->tlv.HSR_TLV_type != HSR_TLV_LIFE_CHECK &&
            hsr_sup_tag->tlv.HSR_TLV_type != PRP_TLV_LIFE_CHECK_DD &&
            hsr_sup_tag->tlv.HSR_TLV_type != PRP_TLV_LIFE_CHECK_DA)
                return false;
        if (hsr_sup_tag->tlv.HSR_TLV_length != 12 &&
            hsr_sup_tag->tlv.HSR_TLV_length != sizeof(struct hsr_sup_payload))
                return false;

        /* Get next tlv */
        total_length += hsr_sup_tag->tlv.HSR_TLV_length;
        if (!pskb_may_pull(skb, total_length))
                return false;
        skb_pull(skb, total_length);
        hsr_sup_tlv = (struct hsr_sup_tlv *)skb->data;
        skb_push(skb, total_length);

        /* if this is a redbox supervision frame we need to verify
         * that more data is available
         */
        if (hsr_sup_tlv->HSR_TLV_type == PRP_TLV_REDBOX_MAC) {
                /* tlv length must be a length of a mac address */
                if (hsr_sup_tlv->HSR_TLV_length != sizeof(struct hsr_sup_payload))
                        return false;

                /* make sure another tlv follows */
                total_length += sizeof(struct hsr_sup_tlv) + hsr_sup_tlv->HSR_TLV_length;
                if (!pskb_may_pull(skb, total_length))
                        return false;

                /* get next tlv */
                skb_pull(skb, total_length);
                hsr_sup_tlv = (struct hsr_sup_tlv *)skb->data;
                skb_push(skb, total_length);
        }

        /* end of tlvs must follow at the end */
        if (hsr_sup_tlv->HSR_TLV_type == HSR_TLV_EOT &&
            hsr_sup_tlv->HSR_TLV_length != 0)
                return false;

        return true;
}

static bool is_proxy_supervision_frame(struct hsr_priv *hsr,
                                       struct sk_buff *skb)
{
        struct hsr_sup_payload *payload;
        struct ethhdr *eth_hdr;
        u16 total_length = 0;

        eth_hdr = (struct ethhdr *)skb_mac_header(skb);

        /* Get the HSR protocol revision. */
        if (eth_hdr->h_proto == htons(ETH_P_HSR))
                total_length = sizeof(struct hsrv1_ethhdr_sp);
        else
                total_length = sizeof(struct hsrv0_ethhdr_sp);

        if (!pskb_may_pull(skb, total_length + sizeof(struct hsr_sup_payload)))
                return false;

        skb_pull(skb, total_length);
        payload = (struct hsr_sup_payload *)skb->data;
        skb_push(skb, total_length);

        /* For RedBox (HSR-SAN) check if we have received the supervision
         * frame with MAC addresses from own ProxyNodeTable.
         */
        return hsr_is_node_in_db(&hsr->proxy_node_db,
                                 payload->macaddress_A);
}

static struct sk_buff *create_stripped_skb_hsr(struct sk_buff *skb_in,
                                               struct hsr_frame_info *frame)
{
        struct sk_buff *skb;
        int copylen;
        unsigned char *dst, *src;

        skb_pull(skb_in, HSR_HLEN);
        skb = __pskb_copy(skb_in, skb_headroom(skb_in) - HSR_HLEN, GFP_ATOMIC);
        skb_push(skb_in, HSR_HLEN);
        if (!skb)
                return NULL;

        skb_reset_mac_header(skb);

        if (skb->ip_summed == CHECKSUM_PARTIAL)
                skb->csum_start -= HSR_HLEN;

        copylen = 2 * ETH_ALEN;
        if (frame->is_vlan)
                copylen += VLAN_HLEN;
        src = skb_mac_header(skb_in);
        dst = skb_mac_header(skb);
        memcpy(dst, src, copylen);

        skb->protocol = eth_hdr(skb)->h_proto;
        return skb;
}

struct sk_buff *hsr_get_untagged_frame(struct hsr_frame_info *frame,
                                       struct hsr_port *port)
{
        if (!frame->skb_std) {
                if (frame->skb_hsr)
                        frame->skb_std =
                                create_stripped_skb_hsr(frame->skb_hsr, frame);
                else
                        netdev_warn_once(port->dev,
                                         "Unexpected frame received in hsr_get_untagged_frame()\n");

                if (!frame->skb_std)
                        return NULL;
        }

        return skb_clone(frame->skb_std, GFP_ATOMIC);
}

struct sk_buff *prp_get_untagged_frame(struct hsr_frame_info *frame,
                                       struct hsr_port *port)
{
        if (!frame->skb_std) {
                if (frame->skb_prp) {
                        /* trim the skb by len - HSR_HLEN to exclude RCT */
                        skb_trim(frame->skb_prp,
                                 frame->skb_prp->len - HSR_HLEN);
                        frame->skb_std =
                                __pskb_copy(frame->skb_prp,
                                            skb_headroom(frame->skb_prp),
                                            GFP_ATOMIC);
                        if (!frame->skb_std)
                                return NULL;
                } else {
                        /* Unexpected */
                        WARN_ONCE(1, "%s:%d: Unexpected frame received (port_src %s)\n",
                                  __FILE__, __LINE__, port->dev->name);
                        return NULL;
                }
        }

        return skb_clone(frame->skb_std, GFP_ATOMIC);
}

static void prp_set_lan_id(struct prp_rct *trailer,
                           struct hsr_port *port)
{
        int lane_id;

        if (port->type == HSR_PT_SLAVE_A)
                lane_id = 0;
        else
                lane_id = 1;

        /* Add net_id in the upper 3 bits of lane_id */
        lane_id |= port->hsr->net_id;
        set_prp_lan_id(trailer, lane_id);
}

/* Tailroom for PRP rct should have been created before calling this */
static struct sk_buff *prp_fill_rct(struct sk_buff *skb,
                                    struct hsr_frame_info *frame,
                                    struct hsr_port *port)
{
        struct prp_rct *trailer;
        int min_size = ETH_ZLEN;
        int lsdu_size;

        if (!skb)
                return skb;

        if (frame->is_vlan)
                min_size = VLAN_ETH_ZLEN;

        if (skb_put_padto(skb, min_size))
                return NULL;

        trailer = (struct prp_rct *)skb_put(skb, HSR_HLEN);
        lsdu_size = skb->len - 14;
        if (frame->is_vlan)
                lsdu_size -= 4;
        prp_set_lan_id(trailer, port);
        set_prp_LSDU_size(trailer, lsdu_size);
        trailer->sequence_nr = htons(frame->sequence_nr);
        trailer->PRP_suffix = htons(ETH_P_PRP);
        skb->protocol = eth_hdr(skb)->h_proto;

        return skb;
}

static void hsr_set_path_id(struct hsr_frame_info *frame,
                            struct hsr_ethhdr *hsr_ethhdr,
                            struct hsr_port *port)
{
        int path_id;

        if (port->hsr->prot_version) {
                if (port->type == HSR_PT_SLAVE_A)
                        path_id = 0;
                else
                        path_id = 1;
        } else {
                if (frame->is_supervision)
                        path_id = 0xf;
                else
                        path_id = 1;
        }

        set_hsr_tag_path(&hsr_ethhdr->hsr_tag, path_id);
}

static struct sk_buff *hsr_fill_tag(struct sk_buff *skb,
                                    struct hsr_frame_info *frame,
                                    struct hsr_port *port, u8 proto_version)
{
        struct hsr_ethhdr *hsr_ethhdr;
        unsigned char *pc;
        int lsdu_size;

        /* pad to minimum packet size which is 60 + 6 (HSR tag) */
        if (skb_put_padto(skb, ETH_ZLEN + HSR_HLEN))
                return NULL;

        lsdu_size = skb->len - 14;
        if (frame->is_vlan)
                lsdu_size -= 4;

        pc = skb_mac_header(skb);
        if (frame->is_vlan)
                /* This 4-byte shift (size of a vlan tag) does not
                 * mean that the ethhdr starts there. But rather it
                 * provides the proper environment for accessing
                 * the fields, such as hsr_tag etc., just like
                 * when the vlan tag is not there. This is because
                 * the hsr tag is after the vlan tag.
                 */
                hsr_ethhdr = (struct hsr_ethhdr *)(pc + VLAN_HLEN);
        else
                hsr_ethhdr = (struct hsr_ethhdr *)pc;

        hsr_set_path_id(frame, hsr_ethhdr, port);
        set_hsr_tag_LSDU_size(&hsr_ethhdr->hsr_tag, lsdu_size);
        hsr_ethhdr->hsr_tag.sequence_nr = htons(frame->sequence_nr);
        hsr_ethhdr->hsr_tag.encap_proto = hsr_ethhdr->ethhdr.h_proto;
        hsr_ethhdr->ethhdr.h_proto = htons(proto_version ?
                        ETH_P_HSR : ETH_P_PRP);
        skb->protocol = hsr_ethhdr->ethhdr.h_proto;

        return skb;
}

/* If the original frame was an HSR tagged frame, just clone it to be sent
 * unchanged. Otherwise, create a private frame especially tagged for 'port'.
 */
struct sk_buff *hsr_create_tagged_frame(struct hsr_frame_info *frame,
                                        struct hsr_port *port)
{
        unsigned char *dst, *src;
        struct sk_buff *skb;
        int movelen;

        if (frame->skb_hsr) {
                struct hsr_ethhdr *hsr_ethhdr =
                        (struct hsr_ethhdr *)skb_mac_header(frame->skb_hsr);

                /* set the lane id properly */
                hsr_set_path_id(frame, hsr_ethhdr, port);
                return skb_clone(frame->skb_hsr, GFP_ATOMIC);
        } else if (port->dev->features & NETIF_F_HW_HSR_TAG_INS) {
                return skb_clone(frame->skb_std, GFP_ATOMIC);
        }

        /* Create the new skb with enough headroom to fit the HSR tag */
        skb = __pskb_copy(frame->skb_std,
                          skb_headroom(frame->skb_std) + HSR_HLEN, GFP_ATOMIC);
        if (!skb)
                return NULL;
        skb_reset_mac_header(skb);

        if (skb->ip_summed == CHECKSUM_PARTIAL)
                skb->csum_start += HSR_HLEN;

        movelen = ETH_HLEN;
        if (frame->is_vlan)
                movelen += VLAN_HLEN;

        src = skb_mac_header(skb);
        dst = skb_push(skb, HSR_HLEN);
        memmove(dst, src, movelen);
        skb_reset_mac_header(skb);

        /* skb_put_padto free skb on error and hsr_fill_tag returns NULL in
         * that case
         */
        return hsr_fill_tag(skb, frame, port, port->hsr->prot_version);
}

struct sk_buff *prp_create_tagged_frame(struct hsr_frame_info *frame,
                                        struct hsr_port *port)
{
        struct sk_buff *skb;

        if (frame->skb_prp) {
                struct prp_rct *trailer = skb_get_PRP_rct(frame->skb_prp);

                if (trailer) {
                        prp_set_lan_id(trailer, port);
                } else {
                        WARN_ONCE(!trailer, "errored PRP skb");
                        return NULL;
                }
                return skb_clone(frame->skb_prp, GFP_ATOMIC);
        } else if (port->dev->features & NETIF_F_HW_HSR_TAG_INS) {
                return skb_clone(frame->skb_std, GFP_ATOMIC);
        }

        skb = skb_copy_expand(frame->skb_std, skb_headroom(frame->skb_std),
                              skb_tailroom(frame->skb_std) + HSR_HLEN,
                              GFP_ATOMIC);
        return prp_fill_rct(skb, frame, port);
}

static void hsr_deliver_master(struct sk_buff *skb, struct net_device *dev,
                               struct hsr_node *node_src)
{
        bool was_multicast_frame;
        int res, recv_len;

        was_multicast_frame = (skb->pkt_type == PACKET_MULTICAST);
        hsr_addr_subst_source(node_src, skb);
        skb_pull(skb, ETH_HLEN);
        recv_len = skb->len;
        res = netif_rx(skb);
        if (res == NET_RX_DROP) {
                dev->stats.rx_dropped++;
        } else {
                dev->stats.rx_packets++;
                dev->stats.rx_bytes += recv_len;
                if (was_multicast_frame)
                        dev->stats.multicast++;
        }
}

static int hsr_xmit(struct sk_buff *skb, struct hsr_port *port,
                    struct hsr_frame_info *frame)
{
        if (frame->port_rcv->type == HSR_PT_MASTER) {
                hsr_addr_subst_dest(frame->node_src, skb, port);

                /* Address substitution (IEC62439-3 pp 26, 50): replace mac
                 * address of outgoing frame with that of the outgoing slave's.
                 */
                ether_addr_copy(eth_hdr(skb)->h_source, port->dev->dev_addr);
        }

        /* When HSR node is used as RedBox - the frame received from HSR ring
         * requires source MAC address (SA) replacement to one which can be
         * recognized by SAN devices (otherwise, frames are dropped by switch)
         */
        if (port->type == HSR_PT_INTERLINK)
                ether_addr_copy(eth_hdr(skb)->h_source,
                                port->hsr->macaddress_redbox);

        return dev_queue_xmit(skb);
}

bool prp_drop_frame(struct hsr_frame_info *frame, struct hsr_port *port)
{
        return ((frame->port_rcv->type == HSR_PT_SLAVE_A &&
                 port->type == HSR_PT_SLAVE_B) ||
                (frame->port_rcv->type == HSR_PT_SLAVE_B &&
                 port->type == HSR_PT_SLAVE_A));
}

bool hsr_drop_frame(struct hsr_frame_info *frame, struct hsr_port *port)
{
        struct sk_buff *skb;

        if (port->dev->features & NETIF_F_HW_HSR_FWD)
                return prp_drop_frame(frame, port);

        /* RedBox specific frames dropping policies
         *
         * Do not send HSR supervisory frames to SAN devices
         */
        if (frame->is_supervision && port->type == HSR_PT_INTERLINK)
                return true;

        /* Do not forward to other HSR port (A or B) unicast frames which
         * are addressed to interlink port (and are in the ProxyNodeTable).
         */
        skb = frame->skb_hsr;
        if (skb && prp_drop_frame(frame, port) &&
            is_unicast_ether_addr(eth_hdr(skb)->h_dest) &&
            hsr_is_node_in_db(&port->hsr->proxy_node_db,
                              eth_hdr(skb)->h_dest)) {
                return true;
        }

        /* Do not forward to port C (Interlink) frames from nodes A and B
         * if DA is in NodeTable.
         */
        if ((frame->port_rcv->type == HSR_PT_SLAVE_A ||
             frame->port_rcv->type == HSR_PT_SLAVE_B) &&
            port->type == HSR_PT_INTERLINK) {
                skb = frame->skb_hsr;
                if (skb && is_unicast_ether_addr(eth_hdr(skb)->h_dest) &&
                    hsr_is_node_in_db(&port->hsr->node_db,
                                      eth_hdr(skb)->h_dest)) {
                        return true;
                }
        }

        /* Do not forward to port A and B unicast frames received on the
         * interlink port if it is addressed to one of nodes registered in
         * the ProxyNodeTable.
         */
        if ((port->type == HSR_PT_SLAVE_A || port->type == HSR_PT_SLAVE_B) &&
            frame->port_rcv->type == HSR_PT_INTERLINK) {
                skb = frame->skb_std;
                if (skb && is_unicast_ether_addr(eth_hdr(skb)->h_dest) &&
                    hsr_is_node_in_db(&port->hsr->proxy_node_db,
                                      eth_hdr(skb)->h_dest)) {
                        return true;
                }
        }

        return false;
}

/* Forward the frame through all devices except:
 * - Back through the receiving device
 * - If it's a HSR frame: through a device where it has passed before
 * - if it's a PRP frame: through another PRP slave device (no bridge)
 * - To the local HSR master only if the frame is directly addressed to it, or
 *   a non-supervision multicast or broadcast frame.
 *
 * HSR slave devices should insert a HSR tag into the frame, or forward the
 * frame unchanged if it's already tagged. Interlink devices should strip HSR
 * tags if they're of the non-HSR type (but only after duplicate discard). The
 * master device always strips HSR tags.
 */
static void hsr_forward_do(struct hsr_frame_info *frame)
{
        struct hsr_port *port;
        struct sk_buff *skb;
        bool sent = false;

        hsr_for_each_port(frame->port_rcv->hsr, port) {
                struct hsr_priv *hsr = port->hsr;
                /* Don't send frame back the way it came */
                if (port == frame->port_rcv)
                        continue;

                /* Don't deliver locally unless we should */
                if (port->type == HSR_PT_MASTER && !frame->is_local_dest)
                        continue;

                /* Deliver frames directly addressed to us to master only */
                if (port->type != HSR_PT_MASTER && frame->is_local_exclusive)
                        continue;

                /* If hardware duplicate generation is enabled, only send out
                 * one port.
                 */
                if ((port->dev->features & NETIF_F_HW_HSR_DUP) && sent)
                        continue;

                /* Don't send frame over port where it has been sent before.
                 * Also for SAN, this shouldn't be done.
                 */
                if (!frame->is_from_san &&
                    hsr->proto_ops->register_frame_out &&
                    hsr->proto_ops->register_frame_out(port, frame))
                        continue;

                if (frame->is_supervision && port->type == HSR_PT_MASTER &&
                    !frame->is_proxy_supervision) {
                        hsr_handle_sup_frame(frame);
                        continue;
                }

                /* Check if frame is to be dropped. Eg. for PRP no forward
                 * between ports, or sending HSR supervision to RedBox.
                 */
                if (hsr->proto_ops->drop_frame &&
                    hsr->proto_ops->drop_frame(frame, port))
                        continue;

                if (port->type == HSR_PT_SLAVE_A ||
                    port->type == HSR_PT_SLAVE_B)
                        skb = hsr->proto_ops->create_tagged_frame(frame, port);
                else
                        skb = hsr->proto_ops->get_untagged_frame(frame, port);

                if (!skb) {
                        frame->port_rcv->dev->stats.rx_dropped++;
                        continue;
                }

                skb->dev = port->dev;
                if (port->type == HSR_PT_MASTER) {
                        hsr_deliver_master(skb, port->dev, frame->node_src);
                } else {
                        if (!hsr_xmit(skb, port, frame))
                                if (port->type == HSR_PT_SLAVE_A ||
                                    port->type == HSR_PT_SLAVE_B)
                                        sent = true;
                }
        }
}

static void check_local_dest(struct hsr_priv *hsr, struct sk_buff *skb,
                             struct hsr_frame_info *frame)
{
        if (hsr_addr_is_self(hsr, eth_hdr(skb)->h_dest)) {
                frame->is_local_exclusive = true;
                skb->pkt_type = PACKET_HOST;
        } else {
                frame->is_local_exclusive = false;
        }

        if (skb->pkt_type == PACKET_HOST ||
            skb->pkt_type == PACKET_MULTICAST ||
            skb->pkt_type == PACKET_BROADCAST) {
                frame->is_local_dest = true;
        } else {
                frame->is_local_dest = false;
        }
}

static void handle_std_frame(struct sk_buff *skb,
                             struct hsr_frame_info *frame)
{
        struct hsr_port *port = frame->port_rcv;
        struct hsr_priv *hsr = port->hsr;

        frame->skb_hsr = NULL;
        frame->skb_prp = NULL;
        frame->skb_std = skb;

        if (port->type != HSR_PT_MASTER)
                frame->is_from_san = true;

        if (port->type == HSR_PT_MASTER ||
            port->type == HSR_PT_INTERLINK) {
                /* Sequence nr for the master/interlink node */
                lockdep_assert_held(&hsr->seqnr_lock);
                frame->sequence_nr = hsr->sequence_nr;
                hsr->sequence_nr++;
        }
}

int hsr_fill_frame_info(__be16 proto, struct sk_buff *skb,
                        struct hsr_frame_info *frame)
{
        struct hsr_port *port = frame->port_rcv;
        struct hsr_priv *hsr = port->hsr;

        /* HSRv0 supervisory frames double as a tag so treat them as tagged. */
        if ((!hsr->prot_version && proto == htons(ETH_P_PRP)) ||
            proto == htons(ETH_P_HSR)) {
                /* Check if skb contains hsr_ethhdr */
                if (skb->mac_len < sizeof(struct hsr_ethhdr))
                        return -EINVAL;

                /* HSR tagged frame :- Data or Supervision */
                frame->skb_std = NULL;
                frame->skb_prp = NULL;
                frame->skb_hsr = skb;
                frame->sequence_nr = hsr_get_skb_sequence_nr(skb);
                return 0;
        }

        /* Standard frame or PRP from master port */
        handle_std_frame(skb, frame);

        return 0;
}

int prp_fill_frame_info(__be16 proto, struct sk_buff *skb,
                        struct hsr_frame_info *frame)
{
        /* Supervision frame */
        struct prp_rct *rct = skb_get_PRP_rct(skb);

        if (rct &&
            prp_check_lsdu_size(skb, rct, frame->is_supervision)) {
                frame->skb_hsr = NULL;
                frame->skb_std = NULL;
                frame->skb_prp = skb;
                frame->sequence_nr = prp_get_skb_sequence_nr(rct);
                return 0;
        }
        handle_std_frame(skb, frame);

        return 0;
}

static int fill_frame_info(struct hsr_frame_info *frame,
                           struct sk_buff *skb, struct hsr_port *port)
{
        struct hsr_priv *hsr = port->hsr;
        struct hsr_vlan_ethhdr *vlan_hdr;
        struct list_head *n_db;
        struct ethhdr *ethhdr;
        __be16 proto;
        int ret;

        /* Check if skb contains ethhdr */
        if (skb->mac_len < sizeof(struct ethhdr))
                return -EINVAL;

        memset(frame, 0, sizeof(*frame));
        frame->is_supervision = is_supervision_frame(port->hsr, skb);
        if (frame->is_supervision && hsr->redbox)
                frame->is_proxy_supervision =
                        is_proxy_supervision_frame(port->hsr, skb);

        n_db = &hsr->node_db;
        if (port->type == HSR_PT_INTERLINK)
                n_db = &hsr->proxy_node_db;

        frame->node_src = hsr_get_node(port, n_db, skb,
                                       frame->is_supervision, port->type);
        if (!frame->node_src)
                return -1; /* Unknown node and !is_supervision, or no mem */

        ethhdr = (struct ethhdr *)skb_mac_header(skb);
        frame->is_vlan = false;
        proto = ethhdr->h_proto;

        if (proto == htons(ETH_P_8021Q))
                frame->is_vlan = true;

        if (frame->is_vlan) {
                /* Note: skb->mac_len might be wrong here. */
                if (!pskb_may_pull(skb,
                                   skb_mac_offset(skb) +
                                   offsetofend(struct hsr_vlan_ethhdr, vlanhdr)))
                        return -EINVAL;
                vlan_hdr = (struct hsr_vlan_ethhdr *)skb_mac_header(skb);
                proto = vlan_hdr->vlanhdr.h_vlan_encapsulated_proto;
        }

        frame->is_from_san = false;
        frame->port_rcv = port;
        ret = hsr->proto_ops->fill_frame_info(proto, skb, frame);
        if (ret)
                return ret;

        check_local_dest(port->hsr, skb, frame);

        return 0;
}

/* Must be called holding rcu read lock (because of the port parameter) */
void hsr_forward_skb(struct sk_buff *skb, struct hsr_port *port)
{
        struct hsr_frame_info frame;

        rcu_read_lock();
        if (fill_frame_info(&frame, skb, port) < 0)
                goto out_drop;

        hsr_register_frame_in(frame.node_src, port, frame.sequence_nr);
        hsr_forward_do(&frame);
        rcu_read_unlock();
        /* Gets called for ingress frames as well as egress from master port.
         * So check and increment stats for master port only here.
         */
        if (port->type == HSR_PT_MASTER || port->type == HSR_PT_INTERLINK) {
                port->dev->stats.tx_packets++;
                port->dev->stats.tx_bytes += skb->len;
        }

        kfree_skb(frame.skb_hsr);
        kfree_skb(frame.skb_prp);
        kfree_skb(frame.skb_std);
        return;

out_drop:
        rcu_read_unlock();
        port->dev->stats.tx_dropped++;
        kfree_skb(skb);
}