Merge tag 'acpi-5.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael...
[sfrench/cifs-2.6.git] / net / 802 / stp.c
1 /*
2  *      STP SAP demux
3  *
4  *      Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
5  *
6  *      This program is free software; you can redistribute it and/or
7  *      modify it under the terms of the GNU General Public License
8  *      version 2 as published by the Free Software Foundation.
9  */
10 #include <linux/mutex.h>
11 #include <linux/skbuff.h>
12 #include <linux/etherdevice.h>
13 #include <linux/llc.h>
14 #include <linux/slab.h>
15 #include <linux/module.h>
16 #include <net/llc.h>
17 #include <net/llc_pdu.h>
18 #include <net/stp.h>
19
20 /* 01:80:c2:00:00:20 - 01:80:c2:00:00:2F */
21 #define GARP_ADDR_MIN   0x20
22 #define GARP_ADDR_MAX   0x2F
23 #define GARP_ADDR_RANGE (GARP_ADDR_MAX - GARP_ADDR_MIN)
24
25 static const struct stp_proto __rcu *garp_protos[GARP_ADDR_RANGE + 1] __read_mostly;
26 static const struct stp_proto __rcu *stp_proto __read_mostly;
27
28 static struct llc_sap *sap __read_mostly;
29 static unsigned int sap_registered;
30 static DEFINE_MUTEX(stp_proto_mutex);
31
32 /* Called under rcu_read_lock from LLC */
33 static int stp_pdu_rcv(struct sk_buff *skb, struct net_device *dev,
34                        struct packet_type *pt, struct net_device *orig_dev)
35 {
36         const struct ethhdr *eh = eth_hdr(skb);
37         const struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
38         const struct stp_proto *proto;
39
40         if (pdu->ssap != LLC_SAP_BSPAN ||
41             pdu->dsap != LLC_SAP_BSPAN ||
42             pdu->ctrl_1 != LLC_PDU_TYPE_U)
43                 goto err;
44
45         if (eh->h_dest[5] >= GARP_ADDR_MIN && eh->h_dest[5] <= GARP_ADDR_MAX) {
46                 proto = rcu_dereference(garp_protos[eh->h_dest[5] -
47                                                     GARP_ADDR_MIN]);
48                 if (proto &&
49                     !ether_addr_equal(eh->h_dest, proto->group_address))
50                         goto err;
51         } else
52                 proto = rcu_dereference(stp_proto);
53
54         if (!proto)
55                 goto err;
56
57         proto->rcv(proto, skb, dev);
58         return 0;
59
60 err:
61         kfree_skb(skb);
62         return 0;
63 }
64
65 int stp_proto_register(const struct stp_proto *proto)
66 {
67         int err = 0;
68
69         mutex_lock(&stp_proto_mutex);
70         if (sap_registered++ == 0) {
71                 sap = llc_sap_open(LLC_SAP_BSPAN, stp_pdu_rcv);
72                 if (!sap) {
73                         err = -ENOMEM;
74                         goto out;
75                 }
76         }
77         if (is_zero_ether_addr(proto->group_address))
78                 rcu_assign_pointer(stp_proto, proto);
79         else
80                 rcu_assign_pointer(garp_protos[proto->group_address[5] -
81                                                GARP_ADDR_MIN], proto);
82 out:
83         mutex_unlock(&stp_proto_mutex);
84         return err;
85 }
86 EXPORT_SYMBOL_GPL(stp_proto_register);
87
88 void stp_proto_unregister(const struct stp_proto *proto)
89 {
90         mutex_lock(&stp_proto_mutex);
91         if (is_zero_ether_addr(proto->group_address))
92                 RCU_INIT_POINTER(stp_proto, NULL);
93         else
94                 RCU_INIT_POINTER(garp_protos[proto->group_address[5] -
95                                                GARP_ADDR_MIN], NULL);
96         synchronize_rcu();
97
98         if (--sap_registered == 0)
99                 llc_sap_put(sap);
100         mutex_unlock(&stp_proto_mutex);
101 }
102 EXPORT_SYMBOL_GPL(stp_proto_unregister);
103
104 MODULE_LICENSE("GPL");