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TOMOYO Linux Cross Reference
Linux/net/ieee802154/6lowpan/tx.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 <net/6lowpan.h>
 12 #include <net/ieee802154_netdev.h>
 13 #include <net/mac802154.h>
 14 
 15 #include "6lowpan_i.h"
 16 
 17 #define LOWPAN_FRAG1_HEAD_SIZE  0x4
 18 #define LOWPAN_FRAGN_HEAD_SIZE  0x5
 19 
 20 /* don't save pan id, it's intra pan */
 21 struct lowpan_addr {
 22         u8 mode;
 23         union {
 24                 /* IPv6 needs big endian here */
 25                 __be64 extended_addr;
 26                 __be16 short_addr;
 27         } u;
 28 };
 29 
 30 struct lowpan_addr_info {
 31         struct lowpan_addr daddr;
 32         struct lowpan_addr saddr;
 33 };
 34 
 35 static inline struct
 36 lowpan_addr_info *lowpan_skb_priv(const struct sk_buff *skb)
 37 {
 38         WARN_ON_ONCE(skb_headroom(skb) < sizeof(struct lowpan_addr_info));
 39         return (struct lowpan_addr_info *)(skb->data -
 40                         sizeof(struct lowpan_addr_info));
 41 }
 42 
 43 /* This callback will be called from AF_PACKET and IPv6 stack, the AF_PACKET
 44  * sockets gives an 8 byte array for addresses only!
 45  *
 46  * TODO I think AF_PACKET DGRAM (sending/receiving) RAW (sending) makes no
 47  * sense here. We should disable it, the right use-case would be AF_INET6
 48  * RAW/DGRAM sockets.
 49  */
 50 int lowpan_header_create(struct sk_buff *skb, struct net_device *ldev,
 51                          unsigned short type, const void *_daddr,
 52                          const void *_saddr, unsigned int len)
 53 {
 54         const u8 *saddr = _saddr;
 55         const u8 *daddr = _daddr;
 56         struct lowpan_addr_info *info;
 57 
 58         /* TODO:
 59          * if this package isn't ipv6 one, where should it be routed?
 60          */
 61         if (type != ETH_P_IPV6)
 62                 return 0;
 63 
 64         if (!saddr)
 65                 saddr = ldev->dev_addr;
 66 
 67         raw_dump_inline(__func__, "saddr", (unsigned char *)saddr, 8);
 68         raw_dump_inline(__func__, "daddr", (unsigned char *)daddr, 8);
 69 
 70         info = lowpan_skb_priv(skb);
 71 
 72         /* TODO: Currently we only support extended_addr */
 73         info->daddr.mode = IEEE802154_ADDR_LONG;
 74         memcpy(&info->daddr.u.extended_addr, daddr,
 75                sizeof(info->daddr.u.extended_addr));
 76         info->saddr.mode = IEEE802154_ADDR_LONG;
 77         memcpy(&info->saddr.u.extended_addr, saddr,
 78                sizeof(info->daddr.u.extended_addr));
 79 
 80         return 0;
 81 }
 82 
 83 static struct sk_buff*
 84 lowpan_alloc_frag(struct sk_buff *skb, int size,
 85                   const struct ieee802154_hdr *master_hdr, bool frag1)
 86 {
 87         struct net_device *wdev = lowpan_dev_info(skb->dev)->wdev;
 88         struct sk_buff *frag;
 89         int rc;
 90 
 91         frag = alloc_skb(wdev->needed_headroom + wdev->needed_tailroom + size,
 92                          GFP_ATOMIC);
 93 
 94         if (likely(frag)) {
 95                 frag->dev = wdev;
 96                 frag->priority = skb->priority;
 97                 skb_reserve(frag, wdev->needed_headroom);
 98                 skb_reset_network_header(frag);
 99                 *mac_cb(frag) = *mac_cb(skb);
100 
101                 if (frag1) {
102                         memcpy(skb_put(frag, skb->mac_len),
103                                skb_mac_header(skb), skb->mac_len);
104                 } else {
105                         rc = wpan_dev_hard_header(frag, wdev,
106                                                   &master_hdr->dest,
107                                                   &master_hdr->source, size);
108                         if (rc < 0) {
109                                 kfree_skb(frag);
110                                 return ERR_PTR(rc);
111                         }
112                 }
113         } else {
114                 frag = ERR_PTR(-ENOMEM);
115         }
116 
117         return frag;
118 }
119 
120 static int
121 lowpan_xmit_fragment(struct sk_buff *skb, const struct ieee802154_hdr *wpan_hdr,
122                      u8 *frag_hdr, int frag_hdrlen,
123                      int offset, int len, bool frag1)
124 {
125         struct sk_buff *frag;
126 
127         raw_dump_inline(__func__, " fragment header", frag_hdr, frag_hdrlen);
128 
129         frag = lowpan_alloc_frag(skb, frag_hdrlen + len, wpan_hdr, frag1);
130         if (IS_ERR(frag))
131                 return PTR_ERR(frag);
132 
133         memcpy(skb_put(frag, frag_hdrlen), frag_hdr, frag_hdrlen);
134         memcpy(skb_put(frag, len), skb_network_header(skb) + offset, len);
135 
136         raw_dump_table(__func__, " fragment dump", frag->data, frag->len);
137 
138         return dev_queue_xmit(frag);
139 }
140 
141 static int
142 lowpan_xmit_fragmented(struct sk_buff *skb, struct net_device *ldev,
143                        const struct ieee802154_hdr *wpan_hdr, u16 dgram_size,
144                        u16 dgram_offset)
145 {
146         __be16 frag_tag;
147         u8 frag_hdr[5];
148         int frag_cap, frag_len, payload_cap, rc;
149         int skb_unprocessed, skb_offset;
150 
151         frag_tag = htons(lowpan_dev_info(ldev)->fragment_tag);
152         lowpan_dev_info(ldev)->fragment_tag++;
153 
154         frag_hdr[0] = LOWPAN_DISPATCH_FRAG1 | ((dgram_size >> 8) & 0x07);
155         frag_hdr[1] = dgram_size & 0xff;
156         memcpy(frag_hdr + 2, &frag_tag, sizeof(frag_tag));
157 
158         payload_cap = ieee802154_max_payload(wpan_hdr);
159 
160         frag_len = round_down(payload_cap - LOWPAN_FRAG1_HEAD_SIZE -
161                               skb_network_header_len(skb), 8);
162 
163         skb_offset = skb_network_header_len(skb);
164         skb_unprocessed = skb->len - skb->mac_len - skb_offset;
165 
166         rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
167                                   LOWPAN_FRAG1_HEAD_SIZE, 0,
168                                   frag_len + skb_network_header_len(skb),
169                                   true);
170         if (rc) {
171                 pr_debug("%s unable to send FRAG1 packet (tag: %d)",
172                          __func__, ntohs(frag_tag));
173                 goto err;
174         }
175 
176         frag_hdr[0] &= ~LOWPAN_DISPATCH_FRAG1;
177         frag_hdr[0] |= LOWPAN_DISPATCH_FRAGN;
178         frag_cap = round_down(payload_cap - LOWPAN_FRAGN_HEAD_SIZE, 8);
179 
180         do {
181                 dgram_offset += frag_len;
182                 skb_offset += frag_len;
183                 skb_unprocessed -= frag_len;
184                 frag_len = min(frag_cap, skb_unprocessed);
185 
186                 frag_hdr[4] = dgram_offset >> 3;
187 
188                 rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
189                                           LOWPAN_FRAGN_HEAD_SIZE, skb_offset,
190                                           frag_len, false);
191                 if (rc) {
192                         pr_debug("%s unable to send a FRAGN packet. (tag: %d, offset: %d)\n",
193                                  __func__, ntohs(frag_tag), skb_offset);
194                         goto err;
195                 }
196         } while (skb_unprocessed > frag_cap);
197 
198         ldev->stats.tx_packets++;
199         ldev->stats.tx_bytes += dgram_size;
200         consume_skb(skb);
201         return NET_XMIT_SUCCESS;
202 
203 err:
204         kfree_skb(skb);
205         return rc;
206 }
207 
208 static int lowpan_header(struct sk_buff *skb, struct net_device *ldev,
209                          u16 *dgram_size, u16 *dgram_offset)
210 {
211         struct wpan_dev *wpan_dev = lowpan_dev_info(ldev)->wdev->ieee802154_ptr;
212         struct ieee802154_addr sa, da;
213         struct ieee802154_mac_cb *cb = mac_cb_init(skb);
214         struct lowpan_addr_info info;
215         void *daddr, *saddr;
216 
217         memcpy(&info, lowpan_skb_priv(skb), sizeof(info));
218 
219         /* TODO: Currently we only support extended_addr */
220         daddr = &info.daddr.u.extended_addr;
221         saddr = &info.saddr.u.extended_addr;
222 
223         *dgram_size = skb->len;
224         lowpan_header_compress(skb, ldev, daddr, saddr);
225         /* dgram_offset = (saved bytes after compression) + lowpan header len */
226         *dgram_offset = (*dgram_size - skb->len) + skb_network_header_len(skb);
227 
228         cb->type = IEEE802154_FC_TYPE_DATA;
229 
230         /* prepare wpan address data */
231         sa.mode = IEEE802154_ADDR_LONG;
232         sa.pan_id = wpan_dev->pan_id;
233         sa.extended_addr = ieee802154_devaddr_from_raw(saddr);
234 
235         /* intra-PAN communications */
236         da.pan_id = sa.pan_id;
237 
238         /* if the destination address is the broadcast address, use the
239          * corresponding short address
240          */
241         if (!memcmp(daddr, ldev->broadcast, EUI64_ADDR_LEN)) {
242                 da.mode = IEEE802154_ADDR_SHORT;
243                 da.short_addr = cpu_to_le16(IEEE802154_ADDR_BROADCAST);
244                 cb->ackreq = false;
245         } else {
246                 da.mode = IEEE802154_ADDR_LONG;
247                 da.extended_addr = ieee802154_devaddr_from_raw(daddr);
248                 cb->ackreq = wpan_dev->ackreq;
249         }
250 
251         return wpan_dev_hard_header(skb, lowpan_dev_info(ldev)->wdev, &da, &sa,
252                                     0);
253 }
254 
255 netdev_tx_t lowpan_xmit(struct sk_buff *skb, struct net_device *ldev)
256 {
257         struct ieee802154_hdr wpan_hdr;
258         int max_single, ret;
259         u16 dgram_size, dgram_offset;
260 
261         pr_debug("package xmit\n");
262 
263         WARN_ON_ONCE(skb->len > IPV6_MIN_MTU);
264 
265         /* We must take a copy of the skb before we modify/replace the ipv6
266          * header as the header could be used elsewhere
267          */
268         skb = skb_unshare(skb, GFP_ATOMIC);
269         if (!skb)
270                 return NET_XMIT_DROP;
271 
272         ret = lowpan_header(skb, ldev, &dgram_size, &dgram_offset);
273         if (ret < 0) {
274                 kfree_skb(skb);
275                 return NET_XMIT_DROP;
276         }
277 
278         if (ieee802154_hdr_peek(skb, &wpan_hdr) < 0) {
279                 kfree_skb(skb);
280                 return NET_XMIT_DROP;
281         }
282 
283         max_single = ieee802154_max_payload(&wpan_hdr);
284 
285         if (skb_tail_pointer(skb) - skb_network_header(skb) <= max_single) {
286                 skb->dev = lowpan_dev_info(ldev)->wdev;
287                 ldev->stats.tx_packets++;
288                 ldev->stats.tx_bytes += dgram_size;
289                 return dev_queue_xmit(skb);
290         } else {
291                 netdev_tx_t rc;
292 
293                 pr_debug("frame is too big, fragmentation is needed\n");
294                 rc = lowpan_xmit_fragmented(skb, ldev, &wpan_hdr, dgram_size,
295                                             dgram_offset);
296 
297                 return rc < 0 ? NET_XMIT_DROP : rc;
298         }
299 }
300 

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