cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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stp.c (2535B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 *	STP SAP demux
      4 *
      5 *	Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
      6 */
      7#include <linux/mutex.h>
      8#include <linux/skbuff.h>
      9#include <linux/etherdevice.h>
     10#include <linux/llc.h>
     11#include <linux/slab.h>
     12#include <linux/module.h>
     13#include <net/llc.h>
     14#include <net/llc_pdu.h>
     15#include <net/stp.h>
     16
     17/* 01:80:c2:00:00:20 - 01:80:c2:00:00:2F */
     18#define GARP_ADDR_MIN	0x20
     19#define GARP_ADDR_MAX	0x2F
     20#define GARP_ADDR_RANGE	(GARP_ADDR_MAX - GARP_ADDR_MIN)
     21
     22static const struct stp_proto __rcu *garp_protos[GARP_ADDR_RANGE + 1] __read_mostly;
     23static const struct stp_proto __rcu *stp_proto __read_mostly;
     24
     25static struct llc_sap *sap __read_mostly;
     26static unsigned int sap_registered;
     27static DEFINE_MUTEX(stp_proto_mutex);
     28
     29/* Called under rcu_read_lock from LLC */
     30static int stp_pdu_rcv(struct sk_buff *skb, struct net_device *dev,
     31		       struct packet_type *pt, struct net_device *orig_dev)
     32{
     33	const struct ethhdr *eh = eth_hdr(skb);
     34	const struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
     35	const struct stp_proto *proto;
     36
     37	if (pdu->ssap != LLC_SAP_BSPAN ||
     38	    pdu->dsap != LLC_SAP_BSPAN ||
     39	    pdu->ctrl_1 != LLC_PDU_TYPE_U)
     40		goto err;
     41
     42	if (eh->h_dest[5] >= GARP_ADDR_MIN && eh->h_dest[5] <= GARP_ADDR_MAX) {
     43		proto = rcu_dereference(garp_protos[eh->h_dest[5] -
     44						    GARP_ADDR_MIN]);
     45		if (proto &&
     46		    !ether_addr_equal(eh->h_dest, proto->group_address))
     47			goto err;
     48	} else
     49		proto = rcu_dereference(stp_proto);
     50
     51	if (!proto)
     52		goto err;
     53
     54	proto->rcv(proto, skb, dev);
     55	return 0;
     56
     57err:
     58	kfree_skb(skb);
     59	return 0;
     60}
     61
     62int stp_proto_register(const struct stp_proto *proto)
     63{
     64	int err = 0;
     65
     66	mutex_lock(&stp_proto_mutex);
     67	if (sap_registered++ == 0) {
     68		sap = llc_sap_open(LLC_SAP_BSPAN, stp_pdu_rcv);
     69		if (!sap) {
     70			err = -ENOMEM;
     71			goto out;
     72		}
     73	}
     74	if (is_zero_ether_addr(proto->group_address))
     75		rcu_assign_pointer(stp_proto, proto);
     76	else
     77		rcu_assign_pointer(garp_protos[proto->group_address[5] -
     78					       GARP_ADDR_MIN], proto);
     79out:
     80	mutex_unlock(&stp_proto_mutex);
     81	return err;
     82}
     83EXPORT_SYMBOL_GPL(stp_proto_register);
     84
     85void stp_proto_unregister(const struct stp_proto *proto)
     86{
     87	mutex_lock(&stp_proto_mutex);
     88	if (is_zero_ether_addr(proto->group_address))
     89		RCU_INIT_POINTER(stp_proto, NULL);
     90	else
     91		RCU_INIT_POINTER(garp_protos[proto->group_address[5] -
     92					       GARP_ADDR_MIN], NULL);
     93	synchronize_rcu();
     94
     95	if (--sap_registered == 0)
     96		llc_sap_put(sap);
     97	mutex_unlock(&stp_proto_mutex);
     98}
     99EXPORT_SYMBOL_GPL(stp_proto_unregister);
    100
    101MODULE_LICENSE("GPL");