blob: 903242111317f14438bc84881358875729e21948 [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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090015#include <linux/slab.h>
Eric W. Biedermane730c152007-09-17 11:53:39 -070016#include <net/net_namespace.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <net/llc.h>
18#include <net/llc_pdu.h>
19#include <net/llc_sap.h>
20
21#if 0
22#define dprintk(args...) printk(KERN_DEBUG args)
23#else
24#define dprintk(args...)
25#endif
26
27/*
28 * Packet handler for the station, registerable because in the minimal
29 * LLC core that is taking shape only the very minimal subset of LLC that
30 * is needed for things like IPX, Appletalk, etc will stay, with all the
31 * rest in the llc1 and llc2 modules.
32 */
33static void (*llc_station_handler)(struct sk_buff *skb);
34
35/*
36 * Packet handlers for LLC_DEST_SAP and LLC_DEST_CONN.
37 */
38static void (*llc_type_handlers[2])(struct llc_sap *sap,
39 struct sk_buff *skb);
40
41void llc_add_pack(int type, void (*handler)(struct llc_sap *sap,
42 struct sk_buff *skb))
43{
44 if (type == LLC_DEST_SAP || type == LLC_DEST_CONN)
45 llc_type_handlers[type - 1] = handler;
46}
47
48void llc_remove_pack(int type)
49{
50 if (type == LLC_DEST_SAP || type == LLC_DEST_CONN)
51 llc_type_handlers[type - 1] = NULL;
52}
53
54void llc_set_station_handler(void (*handler)(struct sk_buff *skb))
55{
56 llc_station_handler = handler;
57}
58
59/**
60 * llc_pdu_type - returns which LLC component must handle for PDU
61 * @skb: input skb
62 *
63 * This function returns which LLC component must handle this PDU.
64 */
65static __inline__ int llc_pdu_type(struct sk_buff *skb)
66{
67 int type = LLC_DEST_CONN; /* I-PDU or S-PDU type */
68 struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
69
70 if ((pdu->ctrl_1 & LLC_PDU_TYPE_MASK) != LLC_PDU_TYPE_U)
71 goto out;
72 switch (LLC_U_PDU_CMD(pdu)) {
73 case LLC_1_PDU_CMD_XID:
74 case LLC_1_PDU_CMD_UI:
75 case LLC_1_PDU_CMD_TEST:
76 type = LLC_DEST_SAP;
77 break;
78 case LLC_2_PDU_CMD_SABME:
79 case LLC_2_PDU_CMD_DISC:
80 case LLC_2_PDU_RSP_UA:
81 case LLC_2_PDU_RSP_DM:
82 case LLC_2_PDU_RSP_FRMR:
83 break;
84 default:
85 type = LLC_DEST_INVALID;
86 break;
87 }
88out:
89 return type;
90}
91
92/**
93 * llc_fixup_skb - initializes skb pointers
94 * @skb: This argument points to incoming skb
95 *
96 * Initializes internal skb pointer to start of network layer by deriving
97 * length of LLC header; finds length of LLC control field in LLC header
98 * by looking at the two lowest-order bits of the first control field
99 * byte; field is either 3 or 4 bytes long.
100 */
101static inline int llc_fixup_skb(struct sk_buff *skb)
102{
103 u8 llc_len = 2;
Jochen Friedrich096f0eb2005-09-22 04:48:46 -0300104 struct llc_pdu_un *pdu;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105
Arnaldo Carvalho de Meloaf426d32005-09-22 03:59:22 -0300106 if (unlikely(!pskb_may_pull(skb, sizeof(*pdu))))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 return 0;
108
Jochen Friedrich096f0eb2005-09-22 04:48:46 -0300109 pdu = (struct llc_pdu_un *)skb->data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110 if ((pdu->ctrl_1 & LLC_PDU_TYPE_MASK) == LLC_PDU_TYPE_U)
111 llc_len = 1;
112 llc_len += 2;
Jochen Friedrich096f0eb2005-09-22 04:48:46 -0300113
114 if (unlikely(!pskb_may_pull(skb, llc_len)))
115 return 0;
116
Arnaldo Carvalho de Melob0e380b2007-04-10 21:21:55 -0700117 skb->transport_header += llc_len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118 skb_pull(skb, llc_len);
119 if (skb->protocol == htons(ETH_P_802_2)) {
Al Viro3fbd4182006-11-08 00:26:05 -0800120 __be16 pdulen = eth_hdr(skb)->h_proto;
Joonwoo Park27785d82008-03-28 16:27:33 -0700121 s32 data_size = ntohs(pdulen) - llc_len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122
Joonwoo Park27785d82008-03-28 16:27:33 -0700123 if (data_size < 0 ||
David S. Milleraa867352011-04-11 18:59:05 -0700124 !pskb_may_pull(skb, data_size))
Joonwoo Park27785d82008-03-28 16:27:33 -0700125 return 0;
David S. Miller5185db02006-04-19 15:37:13 -0700126 if (unlikely(pskb_trim_rcsum(skb, data_size)))
127 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 }
129 return 1;
130}
131
132/**
133 * llc_rcv - 802.2 entry point from net lower layers
134 * @skb: received pdu
135 * @dev: device that receive pdu
136 * @pt: packet type
137 *
138 * When the system receives a 802.2 frame this function is called. It
139 * checks SAP and connection of received pdu and passes frame to
140 * llc_{station,sap,conn}_rcv for sending to proper state machine. If
141 * the frame is related to a busy connection (a connection is sending
142 * data now), it queues this frame in the connection's backlog.
143 */
144int llc_rcv(struct sk_buff *skb, struct net_device *dev,
David S. Millerf2ccd8f2005-08-09 19:34:12 -0700145 struct packet_type *pt, struct net_device *orig_dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146{
147 struct llc_sap *sap;
148 struct llc_pdu_sn *pdu;
149 int dest;
Stephen Hemminger23dbe792006-05-25 15:09:37 -0700150 int (*rcv)(struct sk_buff *, struct net_device *,
151 struct packet_type *, struct net_device *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152
YOSHIFUJI Hideaki721499e2008-07-19 22:34:43 -0700153 if (!net_eq(dev_net(dev), &init_net))
Eric W. Biedermane730c152007-09-17 11:53:39 -0700154 goto drop;
155
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 /*
157 * When the interface is in promisc. mode, drop all the crap that it
158 * receives, do not try to analyse it.
159 */
160 if (unlikely(skb->pkt_type == PACKET_OTHERHOST)) {
Harvey Harrison0dc47872008-03-05 20:47:47 -0800161 dprintk("%s: PACKET_OTHERHOST\n", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 goto drop;
163 }
164 skb = skb_share_check(skb, GFP_ATOMIC);
165 if (unlikely(!skb))
166 goto out;
167 if (unlikely(!llc_fixup_skb(skb)))
168 goto drop;
169 pdu = llc_pdu_sn_hdr(skb);
170 if (unlikely(!pdu->dsap)) /* NULL DSAP, refer to station */
171 goto handle_station;
172 sap = llc_sap_find(pdu->dsap);
173 if (unlikely(!sap)) {/* unknown SAP */
Harvey Harrison0dc47872008-03-05 20:47:47 -0800174 dprintk("%s: llc_sap_find(%02X) failed!\n", __func__,
YOSHIFUJI Hideakid57b1862007-02-09 23:25:01 +0900175 pdu->dsap);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 goto drop;
177 }
178 /*
179 * First the upper layer protocols that don't need the full
180 * LLC functionality
181 */
Stephen Hemminger23dbe792006-05-25 15:09:37 -0700182 rcv = rcu_dereference(sap->rcv_func);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183 dest = llc_pdu_type(skb);
Changli Gao696ea472011-02-22 01:55:18 +0000184 if (unlikely(!dest || !llc_type_handlers[dest - 1])) {
185 if (rcv)
186 rcv(skb, dev, pt, orig_dev);
187 else
188 kfree_skb(skb);
189 } else {
190 if (rcv) {
191 struct sk_buff *cskb = skb_clone(skb, GFP_ATOMIC);
192 if (cskb)
193 rcv(cskb, dev, pt, orig_dev);
194 }
195 llc_type_handlers[dest - 1](sap, skb);
196 }
Arnaldo Carvalho de Melo6e2144b2005-09-22 04:43:05 -0300197 llc_sap_put(sap);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198out:
199 return 0;
200drop:
201 kfree_skb(skb);
202 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203handle_station:
204 if (!llc_station_handler)
205 goto drop;
206 llc_station_handler(skb);
207 goto out;
208}
209
210EXPORT_SYMBOL(llc_add_pack);
211EXPORT_SYMBOL(llc_remove_pack);
212EXPORT_SYMBOL(llc_set_station_handler);