[linux-block.git] / net / 802 / stp.c

// 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_DESCRIPTION("SAP demux for IEEE 802.1D Spanning Tree Protocol (STP)");
MODULE_LICENSE("GPL");
Commit	Line	Data
d2912cb1	1	// SPDX-License-Identifier: GPL-2.0-only
a19800d7 PM	2	/*
	3	* STP SAP demux
	4	*
	5	* Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
a19800d7 PM	6	*/
	7	#include <linux/mutex.h>
	8	#include <linux/skbuff.h>
	9	#include <linux/etherdevice.h>
	10	#include <linux/llc.h>
5a0e3ad6	11	#include <linux/slab.h>
3a9a231d	12	#include <linux/module.h>
a19800d7 PM	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
3cc77ec7 ED	22	static const struct stp_proto __rcu *garp_protos[GARP_ADDR_RANGE + 1] __read_mostly;
3cc77ec7 ED	23	static const struct stp_proto __rcu *stp_proto __read_mostly;
a19800d7 PM	24
	25	static struct llc_sap *sap __read_mostly;
	26	static unsigned int sap_registered;
	27	static DEFINE_MUTEX(stp_proto_mutex);
	28
	29	/* Called under rcu_read_lock from LLC */
	30	static 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 &&
28b29801	46	!ether_addr_equal(eh->h_dest, proto->group_address))
a19800d7 PM	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
	57	err:
	58	kfree_skb(skb);
	59	return 0;
	60	}
	61
	62	int 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);
	79	out:
	80	mutex_unlock(&stp_proto_mutex);
	81	return err;
	82	}
	83	EXPORT_SYMBOL_GPL(stp_proto_register);
	84
	85	void stp_proto_unregister(const struct stp_proto *proto)
	86	{
	87	mutex_lock(&stp_proto_mutex);
	88	if (is_zero_ether_addr(proto->group_address))
a9b3cd7f	89	RCU_INIT_POINTER(stp_proto, NULL);
a19800d7	90	else
a9b3cd7f	91	RCU_INIT_POINTER(garp_protos[proto->group_address[5] -
a19800d7 PM	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	}
	99	EXPORT_SYMBOL_GPL(stp_proto_unregister);
	100
ce1afe28	101	MODULE_DESCRIPTION("SAP demux for IEEE 802.1D Spanning Tree Protocol (STP)");
a19800d7	102	MODULE_LICENSE("GPL");