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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 | */ | |
33 | static void (*llc_station_handler)(struct sk_buff *skb); | |
34 | ||
35 | /* | |
36 | * Packet handlers for LLC_DEST_SAP and LLC_DEST_CONN. | |
37 | */ | |
38 | static void (*llc_type_handlers[2])(struct llc_sap *sap, | |
39 | struct sk_buff *skb); | |
40 | ||
41 | void 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 | ||
48 | void 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 | ||
54 | void 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 | */ | |
65 | static __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 | } | |
88 | out: | |
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 | */ | |
101 | static 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 | 123 | if (data_size < 0 || |
aa867359 | 124 | !pskb_may_pull(skb, data_size)) |
27785d83 | 125 | return 0; |
5185db09 DM |
126 | if (unlikely(pskb_trim_rcsum(skb, data_size))) |
127 | return 0; | |
1da177e4 LT |
128 | } |
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 | */ | |
144 | int llc_rcv(struct sk_buff *skb, struct net_device *dev, | |
f2ccd8fa | 145 | struct packet_type *pt, struct net_device *orig_dev) |
1da177e4 LT |
146 | { |
147 | struct llc_sap *sap; | |
148 | struct llc_pdu_sn *pdu; | |
149 | int dest; | |
23dbe791 SH |
150 | int (*rcv)(struct sk_buff *, struct net_device *, |
151 | struct packet_type *, struct net_device *); | |
1da177e4 | 152 | |
721499e8 | 153 | if (!net_eq(dev_net(dev), &init_net)) |
e730c155 EB |
154 | goto drop; |
155 | ||
1da177e4 LT |
156 | /* |
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)) { | |
0dc47877 | 161 | dprintk("%s: PACKET_OTHERHOST\n", __func__); |
1da177e4 LT |
162 | 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 */ | |
0dc47877 | 174 | dprintk("%s: llc_sap_find(%02X) failed!\n", __func__, |
d57b1869 | 175 | pdu->dsap); |
1da177e4 LT |
176 | goto drop; |
177 | } | |
178 | /* | |
179 | * First the upper layer protocols that don't need the full | |
180 | * LLC functionality | |
181 | */ | |
23dbe791 | 182 | rcv = rcu_dereference(sap->rcv_func); |
1da177e4 | 183 | dest = llc_pdu_type(skb); |
696ea472 CG |
184 | 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 | } | |
6e2144b7 | 197 | llc_sap_put(sap); |
1da177e4 LT |
198 | out: |
199 | return 0; | |
200 | drop: | |
201 | kfree_skb(skb); | |
202 | goto out; | |
203 | handle_station: | |
204 | if (!llc_station_handler) | |
205 | goto drop; | |
206 | llc_station_handler(skb); | |
207 | goto out; | |
208 | } | |
209 | ||
210 | EXPORT_SYMBOL(llc_add_pack); | |
211 | EXPORT_SYMBOL(llc_remove_pack); | |
212 | EXPORT_SYMBOL(llc_set_station_handler); |