blob: e32cab44ea959d8f49781d46580b4204afb7e3cb [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>
Paul Gortmakerbc3b2d72011-07-15 11:47:34 -040016#include <linux/export.h>
Eric W. Biedermane730c152007-09-17 11:53:39 -070017#include <net/net_namespace.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070018#include <net/llc.h>
19#include <net/llc_pdu.h>
20#include <net/llc_sap.h>
21
22#if 0
23#define dprintk(args...) printk(KERN_DEBUG args)
24#else
25#define dprintk(args...)
26#endif
27
28/*
29 * Packet handler for the station, registerable because in the minimal
30 * LLC core that is taking shape only the very minimal subset of LLC that
31 * is needed for things like IPX, Appletalk, etc will stay, with all the
32 * rest in the llc1 and llc2 modules.
33 */
34static void (*llc_station_handler)(struct sk_buff *skb);
35
36/*
37 * Packet handlers for LLC_DEST_SAP and LLC_DEST_CONN.
38 */
39static void (*llc_type_handlers[2])(struct llc_sap *sap,
40 struct sk_buff *skb);
41
42void llc_add_pack(int type, void (*handler)(struct llc_sap *sap,
43 struct sk_buff *skb))
44{
45 if (type == LLC_DEST_SAP || type == LLC_DEST_CONN)
46 llc_type_handlers[type - 1] = handler;
47}
48
49void llc_remove_pack(int type)
50{
51 if (type == LLC_DEST_SAP || type == LLC_DEST_CONN)
52 llc_type_handlers[type - 1] = NULL;
53}
54
55void llc_set_station_handler(void (*handler)(struct sk_buff *skb))
56{
57 llc_station_handler = handler;
58}
59
60/**
61 * llc_pdu_type - returns which LLC component must handle for PDU
62 * @skb: input skb
63 *
64 * This function returns which LLC component must handle this PDU.
65 */
66static __inline__ int llc_pdu_type(struct sk_buff *skb)
67{
68 int type = LLC_DEST_CONN; /* I-PDU or S-PDU type */
69 struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
70
71 if ((pdu->ctrl_1 & LLC_PDU_TYPE_MASK) != LLC_PDU_TYPE_U)
72 goto out;
73 switch (LLC_U_PDU_CMD(pdu)) {
74 case LLC_1_PDU_CMD_XID:
75 case LLC_1_PDU_CMD_UI:
76 case LLC_1_PDU_CMD_TEST:
77 type = LLC_DEST_SAP;
78 break;
79 case LLC_2_PDU_CMD_SABME:
80 case LLC_2_PDU_CMD_DISC:
81 case LLC_2_PDU_RSP_UA:
82 case LLC_2_PDU_RSP_DM:
83 case LLC_2_PDU_RSP_FRMR:
84 break;
85 default:
86 type = LLC_DEST_INVALID;
87 break;
88 }
89out:
90 return type;
91}
92
93/**
94 * llc_fixup_skb - initializes skb pointers
95 * @skb: This argument points to incoming skb
96 *
97 * Initializes internal skb pointer to start of network layer by deriving
98 * length of LLC header; finds length of LLC control field in LLC header
99 * by looking at the two lowest-order bits of the first control field
100 * byte; field is either 3 or 4 bytes long.
101 */
102static inline int llc_fixup_skb(struct sk_buff *skb)
103{
104 u8 llc_len = 2;
Jochen Friedrich096f0eb2005-09-22 04:48:46 -0300105 struct llc_pdu_un *pdu;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106
Arnaldo Carvalho de Meloaf426d32005-09-22 03:59:22 -0300107 if (unlikely(!pskb_may_pull(skb, sizeof(*pdu))))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 return 0;
109
Jochen Friedrich096f0eb2005-09-22 04:48:46 -0300110 pdu = (struct llc_pdu_un *)skb->data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 if ((pdu->ctrl_1 & LLC_PDU_TYPE_MASK) == LLC_PDU_TYPE_U)
112 llc_len = 1;
113 llc_len += 2;
Jochen Friedrich096f0eb2005-09-22 04:48:46 -0300114
115 if (unlikely(!pskb_may_pull(skb, llc_len)))
116 return 0;
117
Arnaldo Carvalho de Melob0e380b2007-04-10 21:21:55 -0700118 skb->transport_header += llc_len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119 skb_pull(skb, llc_len);
120 if (skb->protocol == htons(ETH_P_802_2)) {
Al Viro3fbd4182006-11-08 00:26:05 -0800121 __be16 pdulen = eth_hdr(skb)->h_proto;
Joonwoo Park27785d82008-03-28 16:27:33 -0700122 s32 data_size = ntohs(pdulen) - llc_len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123
Joonwoo Park27785d82008-03-28 16:27:33 -0700124 if (data_size < 0 ||
David S. Milleraa867352011-04-11 18:59:05 -0700125 !pskb_may_pull(skb, data_size))
Joonwoo Park27785d82008-03-28 16:27:33 -0700126 return 0;
David S. Miller5185db02006-04-19 15:37:13 -0700127 if (unlikely(pskb_trim_rcsum(skb, data_size)))
128 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 }
130 return 1;
131}
132
133/**
134 * llc_rcv - 802.2 entry point from net lower layers
135 * @skb: received pdu
136 * @dev: device that receive pdu
137 * @pt: packet type
138 *
139 * When the system receives a 802.2 frame this function is called. It
140 * checks SAP and connection of received pdu and passes frame to
141 * llc_{station,sap,conn}_rcv for sending to proper state machine. If
142 * the frame is related to a busy connection (a connection is sending
143 * data now), it queues this frame in the connection's backlog.
144 */
145int llc_rcv(struct sk_buff *skb, struct net_device *dev,
David S. Millerf2ccd8f2005-08-09 19:34:12 -0700146 struct packet_type *pt, struct net_device *orig_dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147{
148 struct llc_sap *sap;
149 struct llc_pdu_sn *pdu;
150 int dest;
Stephen Hemminger23dbe792006-05-25 15:09:37 -0700151 int (*rcv)(struct sk_buff *, struct net_device *,
152 struct packet_type *, struct net_device *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153
YOSHIFUJI Hideaki721499e2008-07-19 22:34:43 -0700154 if (!net_eq(dev_net(dev), &init_net))
Eric W. Biedermane730c152007-09-17 11:53:39 -0700155 goto drop;
156
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157 /*
158 * When the interface is in promisc. mode, drop all the crap that it
159 * receives, do not try to analyse it.
160 */
161 if (unlikely(skb->pkt_type == PACKET_OTHERHOST)) {
Harvey Harrison0dc47872008-03-05 20:47:47 -0800162 dprintk("%s: PACKET_OTHERHOST\n", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 goto drop;
164 }
165 skb = skb_share_check(skb, GFP_ATOMIC);
166 if (unlikely(!skb))
167 goto out;
168 if (unlikely(!llc_fixup_skb(skb)))
169 goto drop;
170 pdu = llc_pdu_sn_hdr(skb);
171 if (unlikely(!pdu->dsap)) /* NULL DSAP, refer to station */
172 goto handle_station;
173 sap = llc_sap_find(pdu->dsap);
174 if (unlikely(!sap)) {/* unknown SAP */
Harvey Harrison0dc47872008-03-05 20:47:47 -0800175 dprintk("%s: llc_sap_find(%02X) failed!\n", __func__,
YOSHIFUJI Hideakid57b1862007-02-09 23:25:01 +0900176 pdu->dsap);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 goto drop;
178 }
179 /*
180 * First the upper layer protocols that don't need the full
181 * LLC functionality
182 */
Stephen Hemminger23dbe792006-05-25 15:09:37 -0700183 rcv = rcu_dereference(sap->rcv_func);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184 dest = llc_pdu_type(skb);
Changli Gao696ea472011-02-22 01:55:18 +0000185 if (unlikely(!dest || !llc_type_handlers[dest - 1])) {
186 if (rcv)
187 rcv(skb, dev, pt, orig_dev);
188 else
189 kfree_skb(skb);
190 } else {
191 if (rcv) {
192 struct sk_buff *cskb = skb_clone(skb, GFP_ATOMIC);
193 if (cskb)
194 rcv(cskb, dev, pt, orig_dev);
195 }
196 llc_type_handlers[dest - 1](sap, skb);
197 }
Arnaldo Carvalho de Melo6e2144b2005-09-22 04:43:05 -0300198 llc_sap_put(sap);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199out:
200 return 0;
201drop:
202 kfree_skb(skb);
203 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204handle_station:
205 if (!llc_station_handler)
206 goto drop;
207 llc_station_handler(skb);
208 goto out;
209}
210
211EXPORT_SYMBOL(llc_add_pack);
212EXPORT_SYMBOL(llc_remove_pack);
213EXPORT_SYMBOL(llc_set_station_handler);