blob: 57ad974e4d9490b84cca490e2a42d4150f30c81d [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;
Joonwoo Park27785d82008-03-28 16:27:33 -0700120 s32 data_size = ntohs(pdulen) - llc_len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121
Joonwoo Park27785d82008-03-28 16:27:33 -0700122 if (data_size < 0 ||
123 ((skb_tail_pointer(skb) -
124 (u8 *)pdu) - llc_len) < data_size)
125 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);
183 if (rcv) {
YOSHIFUJI Hideakid57b1862007-02-09 23:25:01 +0900184 struct sk_buff *cskb = skb_clone(skb, GFP_ATOMIC);
185 if (cskb)
186 rcv(cskb, dev, pt, orig_dev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 }
188 dest = llc_pdu_type(skb);
189 if (unlikely(!dest || !llc_type_handlers[dest - 1]))
Arnaldo Carvalho de Melo6e2144b2005-09-22 04:43:05 -0300190 goto drop_put;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191 llc_type_handlers[dest - 1](sap, skb);
Arnaldo Carvalho de Melo6e2144b2005-09-22 04:43:05 -0300192out_put:
193 llc_sap_put(sap);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194out:
195 return 0;
196drop:
197 kfree_skb(skb);
198 goto out;
Arnaldo Carvalho de Melo6e2144b2005-09-22 04:43:05 -0300199drop_put:
200 kfree_skb(skb);
201 goto out_put;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202handle_station:
203 if (!llc_station_handler)
204 goto drop;
205 llc_station_handler(skb);
206 goto out;
207}
208
209EXPORT_SYMBOL(llc_add_pack);
210EXPORT_SYMBOL(llc_remove_pack);
211EXPORT_SYMBOL(llc_set_station_handler);