1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *	NET3:	Support for 802.2 demultiplexing off Ethernet
4  *
5  *		Demultiplex 802.2 encoded protocols. We match the entry by the
6  *		SSAP/DSAP pair and then deliver to the registered datalink that
7  *		matches. The control byte is ignored and handling of such items
8  *		is up to the routine passed the frame.
9  *
10  *		Unlike the 802.3 datalink we have a list of 802.2 entries as
11  *		there are multiple protocols to demux. The list is currently
12  *		short (3 or 4 entries at most). The current demux assumes this.
13  */
14 #include <linux/module.h>
15 #include <linux/netdevice.h>
16 #include <linux/skbuff.h>
17 #include <linux/slab.h>
18 #include <net/datalink.h>
19 #include <linux/mm.h>
20 #include <linux/in.h>
21 #include <linux/init.h>
22 #include <net/llc.h>
23 #include <net/p8022.h>
24 
p8022_request(struct datalink_proto * dl,struct sk_buff * skb,const unsigned char * dest)25 static int p8022_request(struct datalink_proto *dl, struct sk_buff *skb,
26 			 const unsigned char *dest)
27 {
28 	llc_build_and_send_ui_pkt(dl->sap, skb, dest, dl->sap->laddr.lsap);
29 	return 0;
30 }
31 
register_8022_client(unsigned char type,int (* func)(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt,struct net_device * orig_dev))32 struct datalink_proto *register_8022_client(unsigned char type,
33 					    int (*func)(struct sk_buff *skb,
34 							struct net_device *dev,
35 							struct packet_type *pt,
36 							struct net_device *orig_dev))
37 {
38 	struct datalink_proto *proto;
39 
40 	proto = kmalloc(sizeof(*proto), GFP_ATOMIC);
41 	if (proto) {
42 		proto->type[0]		= type;
43 		proto->header_length	= 3;
44 		proto->request		= p8022_request;
45 		proto->sap = llc_sap_open(type, func);
46 		if (!proto->sap) {
47 			kfree(proto);
48 			proto = NULL;
49 		}
50 	}
51 	return proto;
52 }
53 
unregister_8022_client(struct datalink_proto * proto)54 void unregister_8022_client(struct datalink_proto *proto)
55 {
56 	llc_sap_put(proto->sap);
57 	kfree(proto);
58 }
59 
60 EXPORT_SYMBOL(register_8022_client);
61 EXPORT_SYMBOL(unregister_8022_client);
62 
63 MODULE_LICENSE("GPL");
64