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

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *	SNAP data link layer. Derived from 802.2
 *
 *		Alan Cox <alan@lxorguk.ukuu.org.uk>,
 *		from the 802.2 layer by Greg Page.
 *		Merged in additions from Greg Page's psnap.c.
 */

#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <net/datalink.h>
#include <net/llc.h>
#include <net/psnap.h>
#include <linux/mm.h>
#include <linux/in.h>
#include <linux/init.h>
#include <linux/rculist.h>

static LIST_HEAD(snap_list);
static DEFINE_SPINLOCK(snap_lock);
static struct llc_sap *snap_sap;

/*
 *	Find a snap client by matching the 5 bytes.
 */
static struct datalink_proto *find_snap_client(const unsigned char *desc)
{
	struct datalink_proto *proto = NULL, *p;

	list_for_each_entry_rcu(p, &snap_list, node, lockdep_is_held(&snap_lock)) {
		if (!memcmp(p->type, desc, 5)) {
			proto = p;
			break;
		}
	}
	return proto;
}

/*
 *	A SNAP packet has arrived
 */
static int snap_rcv(struct sk_buff *skb, struct net_device *dev,
		    struct packet_type *pt, struct net_device *orig_dev)
{
	int rc = 1;
	struct datalink_proto *proto;
	static struct packet_type snap_packet_type = {
		.type = cpu_to_be16(ETH_P_SNAP),
	};

	if (unlikely(!pskb_may_pull(skb, 5)))
		goto drop;

	rcu_read_lock();
	proto = find_snap_client(skb_transport_header(skb));
	if (proto) {
		/* Pass the frame on. */
		skb->transport_header += 5;
		skb_pull_rcsum(skb, 5);
		rc = proto->rcvfunc(skb, dev, &snap_packet_type, orig_dev);
	}
	rcu_read_unlock();

	if (unlikely(!proto))
		goto drop;

out:
	return rc;

drop:
	kfree_skb(skb);
	goto out;
}

/*
 *	Put a SNAP header on a frame and pass to 802.2
 */
static int snap_request(struct datalink_proto *dl,
			struct sk_buff *skb, const u8 *dest)
{
	memcpy(skb_push(skb, 5), dl->type, 5);
	llc_build_and_send_ui_pkt(snap_sap, skb, dest, snap_sap->laddr.lsap);
	return 0;
}

/*
 *	Set up the SNAP layer
 */
EXPORT_SYMBOL(register_snap_client);
EXPORT_SYMBOL(unregister_snap_client);

static const char snap_err_msg[] __initconst =
	KERN_CRIT "SNAP - unable to register with 802.2\n";

static int __init snap_init(void)
{
	snap_sap = llc_sap_open(0xAA, snap_rcv);
	if (!snap_sap) {
		printk(snap_err_msg);
		return -EBUSY;
	}

	return 0;
}

module_init(snap_init);

static void __exit snap_exit(void)
{
	llc_sap_put(snap_sap);
}

module_exit(snap_exit);


/*
 *	Register SNAP clients. We don't yet use this for IP.
 */
struct datalink_proto *register_snap_client(const unsigned char *desc,
					    int (*rcvfunc)(struct sk_buff *,
							   struct net_device *,
							   struct packet_type *,
							   struct net_device *))
{
	struct datalink_proto *proto = NULL;

	spin_lock_bh(&snap_lock);

	if (find_snap_client(desc))
		goto out;

	proto = kmalloc(sizeof(*proto), GFP_ATOMIC);
	if (proto) {
		memcpy(proto->type, desc, 5);
		proto->rcvfunc		= rcvfunc;
		proto->header_length	= 5 + 3; /* snap + 802.2 */
		proto->request		= snap_request;
		list_add_rcu(&proto->node, &snap_list);
	}
out:
	spin_unlock_bh(&snap_lock);

	return proto;
}

/*
 *	Unregister SNAP clients. Protocols no longer want to play with us ...
 */
void unregister_snap_client(struct datalink_proto *proto)
{
	spin_lock_bh(&snap_lock);
	list_del_rcu(&proto->node);
	spin_unlock_bh(&snap_lock);

	synchronize_net();

	kfree(proto);
}

MODULE_LICENSE("GPL");
Commit	Line	Data
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
1da177e4 LT	2	/*
	3	* SNAP data link layer. Derived from 802.2
	4	*
113aa838	5	* Alan Cox <alan@lxorguk.ukuu.org.uk>,
1da177e4 LT	6	* from the 802.2 layer by Greg Page.
1da177e4 LT	7	* Merged in additions from Greg Page's psnap.c.
1da177e4 LT	8	*/
	9
	10	#include <linux/module.h>
	11	#include <linux/netdevice.h>
	12	#include <linux/skbuff.h>
5a0e3ad6	13	#include <linux/slab.h>
1da177e4 LT	14	#include <net/datalink.h>
	15	#include <net/llc.h>
	16	#include <net/psnap.h>
	17	#include <linux/mm.h>
	18	#include <linux/in.h>
	19	#include <linux/init.h>
82524746	20	#include <linux/rculist.h>
1da177e4 LT	21
	22	static LIST_HEAD(snap_list);
	23	static DEFINE_SPINLOCK(snap_lock);
	24	static struct llc_sap *snap_sap;
	25
	26	/*
	27	* Find a snap client by matching the 5 bytes.
	28	*/
7ca98fa2	29	static struct datalink_proto find_snap_client(const unsigned char desc)
1da177e4	30	{
1da177e4 LT	31	struct datalink_proto proto = NULL, p;
1da177e4 LT	32
0a087bf2	33	list_for_each_entry_rcu(p, &snap_list, node, lockdep_is_held(&snap_lock)) {
1da177e4 LT	34	if (!memcmp(p->type, desc, 5)) {
	35	proto = p;
	36	break;
	37	}
	38	}
	39	return proto;
	40	}
	41
	42	/*
	43	* A SNAP packet has arrived
	44	*/
	45	static int snap_rcv(struct sk_buff skb, struct net_device dev,
f2ccd8fa	46	struct packet_type pt, struct net_device orig_dev)
1da177e4 LT	47	{
	48	int rc = 1;
	49	struct datalink_proto *proto;
	50	static struct packet_type snap_packet_type = {
09640e63	51	.type = cpu_to_be16(ETH_P_SNAP),
1da177e4 LT	52	};
1da177e4 LT	53
d92a7db7 HX	54	if (unlikely(!pskb_may_pull(skb, 5)))
	55	goto drop;
	56
1da177e4	57	rcu_read_lock();
9c70220b	58	proto = find_snap_client(skb_transport_header(skb));
1da177e4 LT	59	if (proto) {
1da177e4 LT	60	/* Pass the frame on. */
b0e380b1	61	skb->transport_header += 5;
cbb042f9	62	skb_pull_rcsum(skb, 5);
f2ccd8fa	63	rc = proto->rcvfunc(skb, dev, &snap_packet_type, orig_dev);
1da177e4	64	}
1da177e4	65	rcu_read_unlock();
d92a7db7 HX	66
	67	if (unlikely(!proto))
	68	goto drop;
	69
	70	out:
1da177e4	71	return rc;
d92a7db7 HX	72
	73	drop:
	74	kfree_skb(skb);
	75	goto out;
1da177e4 LT	76	}
	77
	78	/*
	79	* Put a SNAP header on a frame and pass to 802.2
	80	*/
	81	static int snap_request(struct datalink_proto *dl,
2ef6db76	82	struct sk_buff skb, const u8 dest)
1da177e4 LT	83	{
	84	memcpy(skb_push(skb, 5), dl->type, 5);
	85	llc_build_and_send_ui_pkt(snap_sap, skb, dest, snap_sap->laddr.lsap);
	86	return 0;
	87	}
	88
	89	/*
	90	* Set up the SNAP layer
	91	*/
	92	EXPORT_SYMBOL(register_snap_client);
	93	EXPORT_SYMBOL(unregister_snap_client);
	94
0117cfab	95	static const char snap_err_msg[] __initconst =
1da177e4 LT	96	KERN_CRIT "SNAP - unable to register with 802.2\n";
	97
	98	static int __init snap_init(void)
	99	{
	100	snap_sap = llc_sap_open(0xAA, snap_rcv);
0117cfab	101	if (!snap_sap) {
1da177e4	102	printk(snap_err_msg);
0117cfab SH	103	return -EBUSY;
0117cfab SH	104	}
1da177e4 LT	105
	106	return 0;
	107	}
	108
	109	module_init(snap_init);
	110
	111	static void __exit snap_exit(void)
	112	{
6e2144b7	113	llc_sap_put(snap_sap);
1da177e4 LT	114	}
	115
	116	module_exit(snap_exit);
	117
	118
	119	/*
	120	* Register SNAP clients. We don't yet use this for IP.
	121	*/
7ca98fa2	122	struct datalink_proto register_snap_client(const unsigned char desc,
1da177e4	123	int (rcvfunc)(struct sk_buff ,
9afa0949	124	struct net_device *,
f2ccd8fa DM	125	struct packet_type *,
f2ccd8fa DM	126	struct net_device *))
1da177e4 LT	127	{
	128	struct datalink_proto *proto = NULL;
	129
	130	spin_lock_bh(&snap_lock);
	131
	132	if (find_snap_client(desc))
	133	goto out;
	134
	135	proto = kmalloc(sizeof(*proto), GFP_ATOMIC);
	136	if (proto) {
7ca98fa2	137	memcpy(proto->type, desc, 5);
1da177e4 LT	138	proto->rcvfunc = rcvfunc;
	139	proto->header_length = 5 + 3; /* snap + 802.2 */
	140	proto->request = snap_request;
	141	list_add_rcu(&proto->node, &snap_list);
	142	}
	143	out:
	144	spin_unlock_bh(&snap_lock);
	145
1da177e4 LT	146	return proto;
	147	}
	148
	149	/*
	150	* Unregister SNAP clients. Protocols no longer want to play with us ...
	151	*/
	152	void unregister_snap_client(struct datalink_proto *proto)
	153	{
	154	spin_lock_bh(&snap_lock);
	155	list_del_rcu(&proto->node);
	156	spin_unlock_bh(&snap_lock);
	157
	158	synchronize_net();
	159
	160	kfree(proto);
	161	}
	162
	163	MODULE_LICENSE("GPL");