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CommitLineData
1da177e4
LT
1/*
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>
5a0e3ad6 15#include <linux/slab.h>
e730c155 16#include <net/net_namespace.h>
1da177e4
LT
17#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;
096f0eb1 104 struct llc_pdu_un *pdu;
1da177e4 105
af426d32 106 if (unlikely(!pskb_may_pull(skb, sizeof(*pdu))))
1da177e4
LT
107 return 0;
108
096f0eb1 109 pdu = (struct llc_pdu_un *)skb->data;
1da177e4
LT
110 if ((pdu->ctrl_1 & LLC_PDU_TYPE_MASK) == LLC_PDU_TYPE_U)
111 llc_len = 1;
112 llc_len += 2;
096f0eb1
JF
113
114 if (unlikely(!pskb_may_pull(skb, llc_len)))
115 return 0;
116
b0e380b1 117 skb->transport_header += llc_len;
1da177e4
LT
118 skb_pull(skb, llc_len);
119 if (skb->protocol == htons(ETH_P_802_2)) {
3fbd418a 120 __be16 pdulen = eth_hdr(skb)->h_proto;
27785d83 121 s32 data_size = ntohs(pdulen) - llc_len;
1da177e4 122
27785d83
JP
123 if (data_size < 0 ||
124 ((skb_tail_pointer(skb) -
125 (u8 *)pdu) - llc_len) < data_size)
126 return 0;
5185db09
DM
127 if (unlikely(pskb_trim_rcsum(skb, data_size)))
128 return 0;
1da177e4
LT
129 }
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,
f2ccd8fa 146 struct packet_type *pt, struct net_device *orig_dev)
1da177e4
LT
147{
148 struct llc_sap *sap;
149 struct llc_pdu_sn *pdu;
150 int dest;
23dbe791
SH
151 int (*rcv)(struct sk_buff *, struct net_device *,
152 struct packet_type *, struct net_device *);
1da177e4 153
721499e8 154 if (!net_eq(dev_net(dev), &init_net))
e730c155
EB
155 goto drop;
156
1da177e4
LT
157 /*
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)) {
0dc47877 162 dprintk("%s: PACKET_OTHERHOST\n", __func__);
1da177e4
LT
163 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 */
0dc47877 175 dprintk("%s: llc_sap_find(%02X) failed!\n", __func__,
d57b1869 176 pdu->dsap);
1da177e4
LT
177 goto drop;
178 }
179 /*
180 * First the upper layer protocols that don't need the full
181 * LLC functionality
182 */
23dbe791
SH
183 rcv = rcu_dereference(sap->rcv_func);
184 if (rcv) {
d57b1869
YH
185 struct sk_buff *cskb = skb_clone(skb, GFP_ATOMIC);
186 if (cskb)
187 rcv(cskb, dev, pt, orig_dev);
1da177e4
LT
188 }
189 dest = llc_pdu_type(skb);
190 if (unlikely(!dest || !llc_type_handlers[dest - 1]))
6e2144b7 191 goto drop_put;
1da177e4 192 llc_type_handlers[dest - 1](sap, skb);
6e2144b7
ACM
193out_put:
194 llc_sap_put(sap);
1da177e4
LT
195out:
196 return 0;
197drop:
198 kfree_skb(skb);
199 goto out;
6e2144b7
ACM
200drop_put:
201 kfree_skb(skb);
202 goto out_put;
1da177e4
LT
203handle_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);