// SPDX-License-Identifier: GPL-2.0-only
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/*
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* STP SAP demux
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*
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* Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
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*/
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#include <linux/mutex.h>
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#include <linux/skbuff.h>
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#include <linux/etherdevice.h>
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#include <linux/llc.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <net/llc.h>
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#include <net/llc_pdu.h>
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#include <net/stp.h>
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/* 01:80:c2:00:00:20 - 01:80:c2:00:00:2F */
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#define GARP_ADDR_MIN 0x20
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#define GARP_ADDR_MAX 0x2F
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#define GARP_ADDR_RANGE (GARP_ADDR_MAX - GARP_ADDR_MIN)
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static const struct stp_proto __rcu *garp_protos[GARP_ADDR_RANGE + 1] __read_mostly;
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static const struct stp_proto __rcu *stp_proto __read_mostly;
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static struct llc_sap *sap __read_mostly;
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static unsigned int sap_registered;
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static DEFINE_MUTEX(stp_proto_mutex);
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/* Called under rcu_read_lock from LLC */
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static int stp_pdu_rcv(struct sk_buff *skb, struct net_device *dev,
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struct packet_type *pt, struct net_device *orig_dev)
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{
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const struct ethhdr *eh = eth_hdr(skb);
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const struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
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const struct stp_proto *proto;
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if (pdu->ssap != LLC_SAP_BSPAN ||
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pdu->dsap != LLC_SAP_BSPAN ||
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pdu->ctrl_1 != LLC_PDU_TYPE_U)
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goto err;
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if (eh->h_dest[5] >= GARP_ADDR_MIN && eh->h_dest[5] <= GARP_ADDR_MAX) {
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proto = rcu_dereference(garp_protos[eh->h_dest[5] -
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GARP_ADDR_MIN]);
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if (proto &&
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!ether_addr_equal(eh->h_dest, proto->group_address))
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goto err;
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} else
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proto = rcu_dereference(stp_proto);
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if (!proto)
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goto err;
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proto->rcv(proto, skb, dev);
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return 0;
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err:
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kfree_skb(skb);
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return 0;
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}
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int stp_proto_register(const struct stp_proto *proto)
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{
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int err = 0;
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mutex_lock(&stp_proto_mutex);
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if (sap_registered++ == 0) {
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sap = llc_sap_open(LLC_SAP_BSPAN, stp_pdu_rcv);
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if (!sap) {
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err = -ENOMEM;
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goto out;
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}
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}
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if (is_zero_ether_addr(proto->group_address))
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rcu_assign_pointer(stp_proto, proto);
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else
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rcu_assign_pointer(garp_protos[proto->group_address[5] -
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GARP_ADDR_MIN], proto);
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out:
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mutex_unlock(&stp_proto_mutex);
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return err;
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}
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EXPORT_SYMBOL_GPL(stp_proto_register);
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void stp_proto_unregister(const struct stp_proto *proto)
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{
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mutex_lock(&stp_proto_mutex);
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if (is_zero_ether_addr(proto->group_address))
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RCU_INIT_POINTER(stp_proto, NULL);
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else
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RCU_INIT_POINTER(garp_protos[proto->group_address[5] -
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GARP_ADDR_MIN], NULL);
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synchronize_rcu();
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if (--sap_registered == 0)
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llc_sap_put(sap);
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mutex_unlock(&stp_proto_mutex);
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}
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EXPORT_SYMBOL_GPL(stp_proto_unregister);
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MODULE_LICENSE("GPL");
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