| 1 | |
| 2 | |
| 3 | * STP SAP demux
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| 4 | *
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| 5 | * Copyright (c) 2008 Patrick McHardy <[email protected]>
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| 6 |
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| 7 | #include <linux/mutex.h>
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| 8 | #include <linux/skbuff.h>
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| 9 | #include <linux/etherdevice.h>
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| 10 | #include <linux/llc.h>
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| 11 | #include <linux/slab.h>
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| 12 | #include <linux/module.h>
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| 13 | #include <net/llc.h>
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| 14 | #include <net/llc_pdu.h>
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| 15 | #include <net/stp.h>
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| 16 |
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| 17 |
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| 18 | #define GARP_ADDR_MIN 0x20
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| 19 | #define GARP_ADDR_MAX 0x2F
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| 20 | #define GARP_ADDR_RANGE (GARP_ADDR_MAX - GARP_ADDR_MIN)
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| 21 |
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| 22 | static const struct stp_proto __rcu *garp_protos[GARP_ADDR_RANGE + 1] __read_mostly;
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| 23 | static const struct stp_proto __rcu *stp_proto __read_mostly;
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| 24 |
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| 25 | static struct llc_sap *sap __read_mostly;
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| 26 | static unsigned int sap_registered;
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| 27 | static DEFINE_MUTEX(stp_proto_mutex);
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| 28 |
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| 29 |
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| 30 | static int stp_pdu_rcv(struct sk_buff *skb, struct net_device *dev,
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| 31 | struct packet_type *pt, struct net_device *orig_dev)
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| 32 | {
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| 33 | const struct ethhdr *eh = eth_hdr(skb);
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| 34 | const struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
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| 35 | const struct stp_proto *proto;
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| 36 |
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| 37 | if (pdu->ssap != LLC_SAP_BSPAN ||
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| 38 | pdu->dsap != LLC_SAP_BSPAN ||
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| 39 | pdu->ctrl_1 != LLC_PDU_TYPE_U)
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| 40 | goto err;
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| 41 |
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| 42 | if (eh->h_dest[5] >= GARP_ADDR_MIN && eh->h_dest[5] <= GARP_ADDR_MAX) {
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| 43 | proto = rcu_dereference(garp_protos[eh->h_dest[5] -
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| 44 | GARP_ADDR_MIN]);
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| 45 | if (proto &&
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| 46 | !ether_addr_equal(eh->h_dest, proto->group_address))
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| 47 | goto err;
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| 48 | } else
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| 49 | proto = rcu_dereference(stp_proto);
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| 50 |
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| 51 | if (!proto)
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| 52 | goto err;
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| 53 |
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| 54 | proto->rcv(proto, skb, dev);
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| 55 | return 0;
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| 56 |
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| 57 | err:
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| 58 | kfree_skb(skb);
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| 59 | return 0;
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| 60 | }
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| 61 |
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| 62 | int stp_proto_register(const struct stp_proto *proto)
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| 63 | {
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| 64 | int err = 0;
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| 65 |
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| 66 | mutex_lock(&stp_proto_mutex);
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| 67 | if (sap_registered++ == 0) {
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| 68 | sap = llc_sap_open(LLC_SAP_BSPAN, stp_pdu_rcv);
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| 69 | if (!sap) {
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| 70 | err = -ENOMEM;
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| 71 | goto out;
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| 72 | }
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| 73 | }
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| 74 | if (is_zero_ether_addr(proto->group_address))
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| 75 | rcu_assign_pointer(stp_proto, proto);
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| 76 | else
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| 77 | rcu_assign_pointer(garp_protos[proto->group_address[5] -
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| 78 | GARP_ADDR_MIN], proto);
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| 79 | out:
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| 80 | mutex_unlock(&stp_proto_mutex);
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| 81 | return err;
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| 82 | }
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| 83 | EXPORT_SYMBOL_GPL(stp_proto_register);
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| 84 |
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| 85 | void stp_proto_unregister(const struct stp_proto *proto)
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| 86 | {
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| 87 | mutex_lock(&stp_proto_mutex);
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| 88 | if (is_zero_ether_addr(proto->group_address))
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| 89 | RCU_INIT_POINTER(stp_proto, NULL);
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| 90 | else
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| 91 | RCU_INIT_POINTER(garp_protos[proto->group_address[5] -
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| 92 | GARP_ADDR_MIN], NULL);
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| 93 | synchronize_rcu();
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| 94 |
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| 95 | if (--sap_registered == 0)
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| 96 | llc_sap_put(sap);
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| 97 | mutex_unlock(&stp_proto_mutex);
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| 98 | }
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| 99 | EXPORT_SYMBOL_GPL(stp_proto_unregister);
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| 100 |
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| 101 | MODULE_DESCRIPTION("SAP demux for IEEE 802.1D Spanning Tree Protocol (STP)");
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| 102 | MODULE_LICENSE("GPL");
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