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Linux/net/ieee802154/6lowpan/rx.c

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  1 /* This program is free software; you can redistribute it and/or modify
  2  * it under the terms of the GNU General Public License version 2
  3  * as published by the Free Software Foundation.
  4  *
  5  * This program is distributed in the hope that it will be useful,
  6  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  7  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  8  * GNU General Public License for more details.
  9  */
 10 
 11 #include <linux/if_arp.h>
 12 
 13 #include <net/6lowpan.h>
 14 #include <net/mac802154.h>
 15 #include <net/ieee802154_netdev.h>
 16 
 17 #include "6lowpan_i.h"
 18 
 19 #define LOWPAN_DISPATCH_FIRST           0xc0
 20 #define LOWPAN_DISPATCH_FRAG_MASK       0xf8
 21 
 22 #define LOWPAN_DISPATCH_NALP            0x00
 23 #define LOWPAN_DISPATCH_ESC             0x40
 24 #define LOWPAN_DISPATCH_HC1             0x42
 25 #define LOWPAN_DISPATCH_DFF             0x43
 26 #define LOWPAN_DISPATCH_BC0             0x50
 27 #define LOWPAN_DISPATCH_MESH            0x80
 28 
 29 static int lowpan_give_skb_to_device(struct sk_buff *skb)
 30 {
 31         skb->protocol = htons(ETH_P_IPV6);
 32         skb->dev->stats.rx_packets++;
 33         skb->dev->stats.rx_bytes += skb->len;
 34 
 35         return netif_rx(skb);
 36 }
 37 
 38 static int lowpan_rx_handlers_result(struct sk_buff *skb, lowpan_rx_result res)
 39 {
 40         switch (res) {
 41         case RX_CONTINUE:
 42                 /* nobody cared about this packet */
 43                 net_warn_ratelimited("%s: received unknown dispatch\n",
 44                                      __func__);
 45 
 46                 /* fall-through */
 47         case RX_DROP_UNUSABLE:
 48                 kfree_skb(skb);
 49 
 50                 /* fall-through */
 51         case RX_DROP:
 52                 return NET_RX_DROP;
 53         case RX_QUEUED:
 54                 return lowpan_give_skb_to_device(skb);
 55         default:
 56                 break;
 57         }
 58 
 59         return NET_RX_DROP;
 60 }
 61 
 62 static inline bool lowpan_is_frag1(u8 dispatch)
 63 {
 64         return (dispatch & LOWPAN_DISPATCH_FRAG_MASK) == LOWPAN_DISPATCH_FRAG1;
 65 }
 66 
 67 static inline bool lowpan_is_fragn(u8 dispatch)
 68 {
 69         return (dispatch & LOWPAN_DISPATCH_FRAG_MASK) == LOWPAN_DISPATCH_FRAGN;
 70 }
 71 
 72 static lowpan_rx_result lowpan_rx_h_frag(struct sk_buff *skb)
 73 {
 74         int ret;
 75 
 76         if (!(lowpan_is_frag1(*skb_network_header(skb)) ||
 77               lowpan_is_fragn(*skb_network_header(skb))))
 78                 return RX_CONTINUE;
 79 
 80         ret = lowpan_frag_rcv(skb, *skb_network_header(skb) &
 81                               LOWPAN_DISPATCH_FRAG_MASK);
 82         if (ret == 1)
 83                 return RX_QUEUED;
 84 
 85         /* Packet is freed by lowpan_frag_rcv on error or put into the frag
 86          * bucket.
 87          */
 88         return RX_DROP;
 89 }
 90 
 91 int lowpan_iphc_decompress(struct sk_buff *skb)
 92 {
 93         struct ieee802154_hdr hdr;
 94 
 95         if (ieee802154_hdr_peek_addrs(skb, &hdr) < 0)
 96                 return -EINVAL;
 97 
 98         return lowpan_header_decompress(skb, skb->dev, &hdr.dest, &hdr.source);
 99 }
100 
101 static lowpan_rx_result lowpan_rx_h_iphc(struct sk_buff *skb)
102 {
103         int ret;
104 
105         if (!lowpan_is_iphc(*skb_network_header(skb)))
106                 return RX_CONTINUE;
107 
108         /* Setting datagram_offset to zero indicates non frag handling
109          * while doing lowpan_header_decompress.
110          */
111         lowpan_802154_cb(skb)->d_size = 0;
112 
113         ret = lowpan_iphc_decompress(skb);
114         if (ret < 0)
115                 return RX_DROP_UNUSABLE;
116 
117         return RX_QUEUED;
118 }
119 
120 lowpan_rx_result lowpan_rx_h_ipv6(struct sk_buff *skb)
121 {
122         if (!lowpan_is_ipv6(*skb_network_header(skb)))
123                 return RX_CONTINUE;
124 
125         /* Pull off the 1-byte of 6lowpan header. */
126         skb_pull(skb, 1);
127         return RX_QUEUED;
128 }
129 
130 static inline bool lowpan_is_esc(u8 dispatch)
131 {
132         return dispatch == LOWPAN_DISPATCH_ESC;
133 }
134 
135 static lowpan_rx_result lowpan_rx_h_esc(struct sk_buff *skb)
136 {
137         if (!lowpan_is_esc(*skb_network_header(skb)))
138                 return RX_CONTINUE;
139 
140         net_warn_ratelimited("%s: %s\n", skb->dev->name,
141                              "6LoWPAN ESC not supported\n");
142 
143         return RX_DROP_UNUSABLE;
144 }
145 
146 static inline bool lowpan_is_hc1(u8 dispatch)
147 {
148         return dispatch == LOWPAN_DISPATCH_HC1;
149 }
150 
151 static lowpan_rx_result lowpan_rx_h_hc1(struct sk_buff *skb)
152 {
153         if (!lowpan_is_hc1(*skb_network_header(skb)))
154                 return RX_CONTINUE;
155 
156         net_warn_ratelimited("%s: %s\n", skb->dev->name,
157                              "6LoWPAN HC1 not supported\n");
158 
159         return RX_DROP_UNUSABLE;
160 }
161 
162 static inline bool lowpan_is_dff(u8 dispatch)
163 {
164         return dispatch == LOWPAN_DISPATCH_DFF;
165 }
166 
167 static lowpan_rx_result lowpan_rx_h_dff(struct sk_buff *skb)
168 {
169         if (!lowpan_is_dff(*skb_network_header(skb)))
170                 return RX_CONTINUE;
171 
172         net_warn_ratelimited("%s: %s\n", skb->dev->name,
173                              "6LoWPAN DFF not supported\n");
174 
175         return RX_DROP_UNUSABLE;
176 }
177 
178 static inline bool lowpan_is_bc0(u8 dispatch)
179 {
180         return dispatch == LOWPAN_DISPATCH_BC0;
181 }
182 
183 static lowpan_rx_result lowpan_rx_h_bc0(struct sk_buff *skb)
184 {
185         if (!lowpan_is_bc0(*skb_network_header(skb)))
186                 return RX_CONTINUE;
187 
188         net_warn_ratelimited("%s: %s\n", skb->dev->name,
189                              "6LoWPAN BC0 not supported\n");
190 
191         return RX_DROP_UNUSABLE;
192 }
193 
194 static inline bool lowpan_is_mesh(u8 dispatch)
195 {
196         return (dispatch & LOWPAN_DISPATCH_FIRST) == LOWPAN_DISPATCH_MESH;
197 }
198 
199 static lowpan_rx_result lowpan_rx_h_mesh(struct sk_buff *skb)
200 {
201         if (!lowpan_is_mesh(*skb_network_header(skb)))
202                 return RX_CONTINUE;
203 
204         net_warn_ratelimited("%s: %s\n", skb->dev->name,
205                              "6LoWPAN MESH not supported\n");
206 
207         return RX_DROP_UNUSABLE;
208 }
209 
210 static int lowpan_invoke_rx_handlers(struct sk_buff *skb)
211 {
212         lowpan_rx_result res;
213 
214 #define CALL_RXH(rxh)                   \
215         do {                            \
216                 res = rxh(skb); \
217                 if (res != RX_CONTINUE) \
218                         goto rxh_next;  \
219         } while (0)
220 
221         /* likely at first */
222         CALL_RXH(lowpan_rx_h_iphc);
223         CALL_RXH(lowpan_rx_h_frag);
224         CALL_RXH(lowpan_rx_h_ipv6);
225         CALL_RXH(lowpan_rx_h_esc);
226         CALL_RXH(lowpan_rx_h_hc1);
227         CALL_RXH(lowpan_rx_h_dff);
228         CALL_RXH(lowpan_rx_h_bc0);
229         CALL_RXH(lowpan_rx_h_mesh);
230 
231 rxh_next:
232         return lowpan_rx_handlers_result(skb, res);
233 #undef CALL_RXH
234 }
235 
236 static inline bool lowpan_is_nalp(u8 dispatch)
237 {
238         return (dispatch & LOWPAN_DISPATCH_FIRST) == LOWPAN_DISPATCH_NALP;
239 }
240 
241 /* Lookup for reserved dispatch values at:
242  * https://www.iana.org/assignments/_6lowpan-parameters/_6lowpan-parameters.xhtml#_6lowpan-parameters-1
243  *
244  * Last Updated: 2015-01-22
245  */
246 static inline bool lowpan_is_reserved(u8 dispatch)
247 {
248         return ((dispatch >= 0x44 && dispatch <= 0x4F) ||
249                 (dispatch >= 0x51 && dispatch <= 0x5F) ||
250                 (dispatch >= 0xc8 && dispatch <= 0xdf) ||
251                 (dispatch >= 0xe8 && dispatch <= 0xff));
252 }
253 
254 /* lowpan_rx_h_check checks on generic 6LoWPAN requirements
255  * in MAC and 6LoWPAN header.
256  *
257  * Don't manipulate the skb here, it could be shared buffer.
258  */
259 static inline bool lowpan_rx_h_check(struct sk_buff *skb)
260 {
261         __le16 fc = ieee802154_get_fc_from_skb(skb);
262 
263         /* check on ieee802154 conform 6LoWPAN header */
264         if (!ieee802154_is_data(fc) ||
265             !ieee802154_skb_is_intra_pan_addressing(fc, skb))
266                 return false;
267 
268         /* check if we can dereference the dispatch */
269         if (unlikely(!skb->len))
270                 return false;
271 
272         if (lowpan_is_nalp(*skb_network_header(skb)) ||
273             lowpan_is_reserved(*skb_network_header(skb)))
274                 return false;
275 
276         return true;
277 }
278 
279 static int lowpan_rcv(struct sk_buff *skb, struct net_device *wdev,
280                       struct packet_type *pt, struct net_device *orig_wdev)
281 {
282         struct net_device *ldev;
283 
284         if (wdev->type != ARPHRD_IEEE802154 ||
285             skb->pkt_type == PACKET_OTHERHOST ||
286             !lowpan_rx_h_check(skb))
287                 goto drop;
288 
289         ldev = wdev->ieee802154_ptr->lowpan_dev;
290         if (!ldev || !netif_running(ldev))
291                 goto drop;
292 
293         /* Replacing skb->dev and followed rx handlers will manipulate skb. */
294         skb = skb_share_check(skb, GFP_ATOMIC);
295         if (!skb)
296                 goto out;
297         skb->dev = ldev;
298 
299         /* When receive frag1 it's likely that we manipulate the buffer.
300          * When recevie iphc we manipulate the data buffer. So we need
301          * to unshare the buffer.
302          */
303         if (lowpan_is_frag1(*skb_network_header(skb)) ||
304             lowpan_is_iphc(*skb_network_header(skb))) {
305                 skb = skb_unshare(skb, GFP_ATOMIC);
306                 if (!skb)
307                         goto out;
308         }
309 
310         return lowpan_invoke_rx_handlers(skb);
311 
312 drop:
313         kfree_skb(skb);
314 out:
315         return NET_RX_DROP;
316 }
317 
318 static struct packet_type lowpan_packet_type = {
319         .type = htons(ETH_P_IEEE802154),
320         .func = lowpan_rcv,
321 };
322 
323 void lowpan_rx_init(void)
324 {
325         dev_add_pack(&lowpan_packet_type);
326 }
327 
328 void lowpan_rx_exit(void)
329 {
330         dev_remove_pack(&lowpan_packet_type);
331 }
332 

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