1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * STP SAP demux |
4 | * |
5 | * Copyright (c) 2008 Patrick McHardy <kaber@trash.net> |
6 | */ |
7 | #include <linux/mutex.h> |
8 | #include <linux/skbuff.h> |
9 | #include <linux/etherdevice.h> |
10 | #include <linux/llc.h> |
11 | #include <linux/slab.h> |
12 | #include <linux/module.h> |
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 | |
22 | static const struct stp_proto __rcu *garp_protos[GARP_ADDR_RANGE + 1] __read_mostly; |
23 | static const struct stp_proto __rcu *stp_proto __read_mostly; |
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 && |
46 | !ether_addr_equal(addr1: eh->h_dest, addr2: proto->group_address)) |
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, rcv: stp_pdu_rcv); |
69 | if (!sap) { |
70 | err = -ENOMEM; |
71 | goto out; |
72 | } |
73 | } |
74 | if (is_zero_ether_addr(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(lock: &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(addr: proto->group_address)) |
89 | RCU_INIT_POINTER(stp_proto, NULL); |
90 | else |
91 | RCU_INIT_POINTER(garp_protos[proto->group_address[5] - |
92 | GARP_ADDR_MIN], NULL); |
93 | synchronize_rcu(); |
94 | |
95 | if (--sap_registered == 0) |
96 | llc_sap_put(sap); |
97 | mutex_unlock(lock: &stp_proto_mutex); |
98 | } |
99 | EXPORT_SYMBOL_GPL(stp_proto_unregister); |
100 | |
101 | MODULE_DESCRIPTION("SAP demux for IEEE 802.1D Spanning Tree Protocol (STP)" ); |
102 | MODULE_LICENSE("GPL" ); |
103 | |