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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
a19800d7 PM |
2 | /* |
3 | * STP SAP demux | |
4 | * | |
5 | * Copyright (c) 2008 Patrick McHardy <kaber@trash.net> | |
a19800d7 PM |
6 | */ |
7 | #include <linux/mutex.h> | |
8 | #include <linux/skbuff.h> | |
9 | #include <linux/etherdevice.h> | |
10 | #include <linux/llc.h> | |
5a0e3ad6 | 11 | #include <linux/slab.h> |
3a9a231d | 12 | #include <linux/module.h> |
a19800d7 PM |
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 | ||
3cc77ec7 ED |
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; | |
a19800d7 PM |
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 && | |
28b29801 | 46 | !ether_addr_equal(eh->h_dest, proto->group_address)) |
a19800d7 PM |
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, stp_pdu_rcv); | |
69 | if (!sap) { | |
70 | err = -ENOMEM; | |
71 | goto out; | |
72 | } | |
73 | } | |
74 | if (is_zero_ether_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(&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(proto->group_address)) | |
a9b3cd7f | 89 | RCU_INIT_POINTER(stp_proto, NULL); |
a19800d7 | 90 | else |
a9b3cd7f | 91 | RCU_INIT_POINTER(garp_protos[proto->group_address[5] - |
a19800d7 PM |
92 | GARP_ADDR_MIN], NULL); |
93 | synchronize_rcu(); | |
94 | ||
95 | if (--sap_registered == 0) | |
96 | llc_sap_put(sap); | |
97 | mutex_unlock(&stp_proto_mutex); | |
98 | } | |
99 | EXPORT_SYMBOL_GPL(stp_proto_unregister); | |
100 | ||
101 | MODULE_LICENSE("GPL"); |