blob: c40c9b2a345aca6058d222ad662f4a830c943d7e [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * llc_input.c - Minimal input path for LLC
3 *
4 * Copyright (c) 1997 by Procom Technology, Inc.
5 * 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
6 *
7 * This program can be redistributed or modified under the terms of the
8 * GNU General Public License as published by the Free Software Foundation.
9 * This program is distributed without any warranty or implied warranty
10 * of merchantability or fitness for a particular purpose.
11 *
12 * See the GNU General Public License for more details.
13 */
14#include <linux/netdevice.h>
Eric W. Biedermane730c152007-09-17 11:53:39 -070015#include <net/net_namespace.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016#include <net/llc.h>
17#include <net/llc_pdu.h>
18#include <net/llc_sap.h>
19
20#if 0
21#define dprintk(args...) printk(KERN_DEBUG args)
22#else
23#define dprintk(args...)
24#endif
25
26/*
27 * Packet handler for the station, registerable because in the minimal
28 * LLC core that is taking shape only the very minimal subset of LLC that
29 * is needed for things like IPX, Appletalk, etc will stay, with all the
30 * rest in the llc1 and llc2 modules.
31 */
32static void (*llc_station_handler)(struct sk_buff *skb);
33
34/*
35 * Packet handlers for LLC_DEST_SAP and LLC_DEST_CONN.
36 */
37static void (*llc_type_handlers[2])(struct llc_sap *sap,
38 struct sk_buff *skb);
39
40void llc_add_pack(int type, void (*handler)(struct llc_sap *sap,
41 struct sk_buff *skb))
42{
43 if (type == LLC_DEST_SAP || type == LLC_DEST_CONN)
44 llc_type_handlers[type - 1] = handler;
45}
46
47void llc_remove_pack(int type)
48{
49 if (type == LLC_DEST_SAP || type == LLC_DEST_CONN)
50 llc_type_handlers[type - 1] = NULL;
51}
52
53void llc_set_station_handler(void (*handler)(struct sk_buff *skb))
54{
55 llc_station_handler = handler;
56}
57
58/**
59 * llc_pdu_type - returns which LLC component must handle for PDU
60 * @skb: input skb
61 *
62 * This function returns which LLC component must handle this PDU.
63 */
64static __inline__ int llc_pdu_type(struct sk_buff *skb)
65{
66 int type = LLC_DEST_CONN; /* I-PDU or S-PDU type */
67 struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
68
69 if ((pdu->ctrl_1 & LLC_PDU_TYPE_MASK) != LLC_PDU_TYPE_U)
70 goto out;
71 switch (LLC_U_PDU_CMD(pdu)) {
72 case LLC_1_PDU_CMD_XID:
73 case LLC_1_PDU_CMD_UI:
74 case LLC_1_PDU_CMD_TEST:
75 type = LLC_DEST_SAP;
76 break;
77 case LLC_2_PDU_CMD_SABME:
78 case LLC_2_PDU_CMD_DISC:
79 case LLC_2_PDU_RSP_UA:
80 case LLC_2_PDU_RSP_DM:
81 case LLC_2_PDU_RSP_FRMR:
82 break;
83 default:
84 type = LLC_DEST_INVALID;
85 break;
86 }
87out:
88 return type;
89}
90
91/**
92 * llc_fixup_skb - initializes skb pointers
93 * @skb: This argument points to incoming skb
94 *
95 * Initializes internal skb pointer to start of network layer by deriving
96 * length of LLC header; finds length of LLC control field in LLC header
97 * by looking at the two lowest-order bits of the first control field
98 * byte; field is either 3 or 4 bytes long.
99 */
100static inline int llc_fixup_skb(struct sk_buff *skb)
101{
102 u8 llc_len = 2;
Jochen Friedrich096f0eb2005-09-22 04:48:46 -0300103 struct llc_pdu_un *pdu;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104
Arnaldo Carvalho de Meloaf426d32005-09-22 03:59:22 -0300105 if (unlikely(!pskb_may_pull(skb, sizeof(*pdu))))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 return 0;
107
Jochen Friedrich096f0eb2005-09-22 04:48:46 -0300108 pdu = (struct llc_pdu_un *)skb->data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109 if ((pdu->ctrl_1 & LLC_PDU_TYPE_MASK) == LLC_PDU_TYPE_U)
110 llc_len = 1;
111 llc_len += 2;
Jochen Friedrich096f0eb2005-09-22 04:48:46 -0300112
113 if (unlikely(!pskb_may_pull(skb, llc_len)))
114 return 0;
115
Arnaldo Carvalho de Melob0e380b2007-04-10 21:21:55 -0700116 skb->transport_header += llc_len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 skb_pull(skb, llc_len);
118 if (skb->protocol == htons(ETH_P_802_2)) {
Al Viro3fbd4182006-11-08 00:26:05 -0800119 __be16 pdulen = eth_hdr(skb)->h_proto;
120 u16 data_size = ntohs(pdulen) - llc_len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121
David S. Miller5185db02006-04-19 15:37:13 -0700122 if (unlikely(pskb_trim_rcsum(skb, data_size)))
123 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124 }
125 return 1;
126}
127
128/**
129 * llc_rcv - 802.2 entry point from net lower layers
130 * @skb: received pdu
131 * @dev: device that receive pdu
132 * @pt: packet type
133 *
134 * When the system receives a 802.2 frame this function is called. It
135 * checks SAP and connection of received pdu and passes frame to
136 * llc_{station,sap,conn}_rcv for sending to proper state machine. If
137 * the frame is related to a busy connection (a connection is sending
138 * data now), it queues this frame in the connection's backlog.
139 */
140int llc_rcv(struct sk_buff *skb, struct net_device *dev,
David S. Millerf2ccd8f2005-08-09 19:34:12 -0700141 struct packet_type *pt, struct net_device *orig_dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142{
143 struct llc_sap *sap;
144 struct llc_pdu_sn *pdu;
145 int dest;
Stephen Hemminger23dbe792006-05-25 15:09:37 -0700146 int (*rcv)(struct sk_buff *, struct net_device *,
147 struct packet_type *, struct net_device *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148
Eric W. Biedermane730c152007-09-17 11:53:39 -0700149 if (dev->nd_net != &init_net)
150 goto drop;
151
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 /*
153 * When the interface is in promisc. mode, drop all the crap that it
154 * receives, do not try to analyse it.
155 */
156 if (unlikely(skb->pkt_type == PACKET_OTHERHOST)) {
157 dprintk("%s: PACKET_OTHERHOST\n", __FUNCTION__);
158 goto drop;
159 }
160 skb = skb_share_check(skb, GFP_ATOMIC);
161 if (unlikely(!skb))
162 goto out;
163 if (unlikely(!llc_fixup_skb(skb)))
164 goto drop;
165 pdu = llc_pdu_sn_hdr(skb);
166 if (unlikely(!pdu->dsap)) /* NULL DSAP, refer to station */
167 goto handle_station;
168 sap = llc_sap_find(pdu->dsap);
169 if (unlikely(!sap)) {/* unknown SAP */
170 dprintk("%s: llc_sap_find(%02X) failed!\n", __FUNCTION__,
YOSHIFUJI Hideakid57b1862007-02-09 23:25:01 +0900171 pdu->dsap);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 goto drop;
173 }
174 /*
175 * First the upper layer protocols that don't need the full
176 * LLC functionality
177 */
Stephen Hemminger23dbe792006-05-25 15:09:37 -0700178 rcv = rcu_dereference(sap->rcv_func);
179 if (rcv) {
YOSHIFUJI Hideakid57b1862007-02-09 23:25:01 +0900180 struct sk_buff *cskb = skb_clone(skb, GFP_ATOMIC);
181 if (cskb)
182 rcv(cskb, dev, pt, orig_dev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183 }
184 dest = llc_pdu_type(skb);
185 if (unlikely(!dest || !llc_type_handlers[dest - 1]))
Arnaldo Carvalho de Melo6e2144b2005-09-22 04:43:05 -0300186 goto drop_put;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 llc_type_handlers[dest - 1](sap, skb);
Arnaldo Carvalho de Melo6e2144b2005-09-22 04:43:05 -0300188out_put:
189 llc_sap_put(sap);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190out:
191 return 0;
192drop:
193 kfree_skb(skb);
194 goto out;
Arnaldo Carvalho de Melo6e2144b2005-09-22 04:43:05 -0300195drop_put:
196 kfree_skb(skb);
197 goto out_put;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198handle_station:
199 if (!llc_station_handler)
200 goto drop;
201 llc_station_handler(skb);
202 goto out;
203}
204
205EXPORT_SYMBOL(llc_add_pack);
206EXPORT_SYMBOL(llc_remove_pack);
207EXPORT_SYMBOL(llc_set_station_handler);