net/802/p8022.c

   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
  25 static int p8022_request(struct datalink_proto *dl, struct sk_buff *skb,
  26                          unsigned char *dest)
  27 {
  28         llc_build_and_send_ui_pkt(dl->sap, skb, dest, dl->sap->laddr.lsap);
  29         return 0;
  30 }
  31
  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
  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");