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