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CommitLineData
7240cdec
AA
1/* 6LoWPAN fragment reassembly
2 *
3 *
4 * Authors:
5 * Alexander Aring <aar@pengutronix.de>
6 *
7 * Based on: net/ipv6/reassembly.c
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * as published by the Free Software Foundation; either version
12 * 2 of the License, or (at your option) any later version.
13 */
14
15#define pr_fmt(fmt) "6LoWPAN: " fmt
16
17#include <linux/net.h>
18#include <linux/list.h>
19#include <linux/netdevice.h>
20#include <linux/random.h>
21#include <linux/jhash.h>
22#include <linux/skbuff.h>
23#include <linux/slab.h>
24#include <linux/export.h>
25
26#include <net/ieee802154_netdev.h>
cefc8c8a 27#include <net/6lowpan.h>
7240cdec
AA
28#include <net/ipv6.h>
29#include <net/inet_frag.h>
30
7240cdec
AA
31#include "reassembly.h"
32
d4ad4d22
NA
33static const char lowpan_frags_cache_name[] = "lowpan-frags";
34
a13061ec 35struct lowpan_frag_info {
f870b8c6 36 u16 d_tag;
a13061ec
PB
37 u16 d_size;
38 u8 d_offset;
39};
40
94716d2f 41static struct lowpan_frag_info *lowpan_cb(struct sk_buff *skb)
a13061ec
PB
42{
43 return (struct lowpan_frag_info *)skb->cb;
44}
45
7240cdec
AA
46static struct inet_frags lowpan_frags;
47
48static int lowpan_frag_reasm(struct lowpan_frag_queue *fq,
49 struct sk_buff *prev, struct net_device *dev);
50
f870b8c6 51static unsigned int lowpan_hash_frag(u16 tag, u16 d_size,
ae531b94
PB
52 const struct ieee802154_addr *saddr,
53 const struct ieee802154_addr *daddr)
7240cdec 54{
7240cdec 55 net_get_random_once(&lowpan_frags.rnd, sizeof(lowpan_frags.rnd));
fb3cfe6e
FW
56 return jhash_3words(ieee802154_addr_hash(saddr),
57 ieee802154_addr_hash(daddr),
58 (__force u32)(tag + (d_size << 16)),
59 lowpan_frags.rnd);
7240cdec
AA
60}
61
36c77782 62static unsigned int lowpan_hashfn(const struct inet_frag_queue *q)
7240cdec 63{
36c77782 64 const struct lowpan_frag_queue *fq;
7240cdec
AA
65
66 fq = container_of(q, struct lowpan_frag_queue, q);
67 return lowpan_hash_frag(fq->tag, fq->d_size, &fq->saddr, &fq->daddr);
68}
69
36c77782 70static bool lowpan_frag_match(const struct inet_frag_queue *q, const void *a)
7240cdec 71{
36c77782
FW
72 const struct lowpan_frag_queue *fq;
73 const struct lowpan_create_arg *arg = a;
7240cdec
AA
74
75 fq = container_of(q, struct lowpan_frag_queue, q);
76 return fq->tag == arg->tag && fq->d_size == arg->d_size &&
ae531b94
PB
77 ieee802154_addr_equal(&fq->saddr, arg->src) &&
78 ieee802154_addr_equal(&fq->daddr, arg->dst);
7240cdec 79}
7240cdec 80
36c77782 81static void lowpan_frag_init(struct inet_frag_queue *q, const void *a)
7240cdec 82{
36c77782 83 const struct lowpan_create_arg *arg = a;
7240cdec 84 struct lowpan_frag_queue *fq;
7240cdec
AA
85
86 fq = container_of(q, struct lowpan_frag_queue, q);
87
88 fq->tag = arg->tag;
89 fq->d_size = arg->d_size;
90 fq->saddr = *arg->src;
91 fq->daddr = *arg->dst;
92}
7240cdec
AA
93
94static void lowpan_frag_expire(unsigned long data)
95{
96 struct frag_queue *fq;
97 struct net *net;
98
99 fq = container_of((struct inet_frag_queue *)data, struct frag_queue, q);
100 net = container_of(fq->q.net, struct net, ieee802154_lowpan.frags);
101
17794326
FW
102 spin_lock(&fq->q.lock);
103
06aa8b8a 104 if (fq->q.flags & INET_FRAG_COMPLETE)
17794326
FW
105 goto out;
106
107 inet_frag_kill(&fq->q, &lowpan_frags);
108out:
109 spin_unlock(&fq->q.lock);
110 inet_frag_put(&fq->q, &lowpan_frags);
7240cdec
AA
111}
112
113static inline struct lowpan_frag_queue *
a13061ec 114fq_find(struct net *net, const struct lowpan_frag_info *frag_info,
ae531b94
PB
115 const struct ieee802154_addr *src,
116 const struct ieee802154_addr *dst)
7240cdec
AA
117{
118 struct inet_frag_queue *q;
119 struct lowpan_create_arg arg;
120 unsigned int hash;
599018a7
LR
121 struct netns_ieee802154_lowpan *ieee802154_lowpan =
122 net_ieee802154_lowpan(net);
7240cdec
AA
123
124 arg.tag = frag_info->d_tag;
125 arg.d_size = frag_info->d_size;
126 arg.src = src;
127 arg.dst = dst;
128
7240cdec
AA
129 hash = lowpan_hash_frag(frag_info->d_tag, frag_info->d_size, src, dst);
130
599018a7 131 q = inet_frag_find(&ieee802154_lowpan->frags,
7240cdec
AA
132 &lowpan_frags, &arg, hash);
133 if (IS_ERR_OR_NULL(q)) {
134 inet_frag_maybe_warn_overflow(q, pr_fmt());
135 return NULL;
136 }
137 return container_of(q, struct lowpan_frag_queue, q);
138}
139
140static int lowpan_frag_queue(struct lowpan_frag_queue *fq,
141 struct sk_buff *skb, const u8 frag_type)
142{
143 struct sk_buff *prev, *next;
144 struct net_device *dev;
145 int end, offset;
146
06aa8b8a 147 if (fq->q.flags & INET_FRAG_COMPLETE)
7240cdec
AA
148 goto err;
149
a13061ec
PB
150 offset = lowpan_cb(skb)->d_offset << 3;
151 end = lowpan_cb(skb)->d_size;
7240cdec
AA
152
153 /* Is this the final fragment? */
154 if (offset + skb->len == end) {
155 /* If we already have some bits beyond end
156 * or have different end, the segment is corrupted.
157 */
158 if (end < fq->q.len ||
06aa8b8a 159 ((fq->q.flags & INET_FRAG_LAST_IN) && end != fq->q.len))
7240cdec 160 goto err;
06aa8b8a 161 fq->q.flags |= INET_FRAG_LAST_IN;
7240cdec
AA
162 fq->q.len = end;
163 } else {
164 if (end > fq->q.len) {
165 /* Some bits beyond end -> corruption. */
06aa8b8a 166 if (fq->q.flags & INET_FRAG_LAST_IN)
7240cdec
AA
167 goto err;
168 fq->q.len = end;
169 }
170 }
171
172 /* Find out which fragments are in front and at the back of us
173 * in the chain of fragments so far. We must know where to put
174 * this fragment, right?
175 */
176 prev = fq->q.fragments_tail;
a13061ec 177 if (!prev || lowpan_cb(prev)->d_offset < lowpan_cb(skb)->d_offset) {
7240cdec
AA
178 next = NULL;
179 goto found;
180 }
181 prev = NULL;
182 for (next = fq->q.fragments; next != NULL; next = next->next) {
a13061ec 183 if (lowpan_cb(next)->d_offset >= lowpan_cb(skb)->d_offset)
7240cdec
AA
184 break; /* bingo! */
185 prev = next;
186 }
187
188found:
189 /* Insert this fragment in the chain of fragments. */
190 skb->next = next;
191 if (!next)
192 fq->q.fragments_tail = skb;
193 if (prev)
194 prev->next = skb;
195 else
196 fq->q.fragments = skb;
197
198 dev = skb->dev;
199 if (dev)
200 skb->dev = NULL;
201
202 fq->q.stamp = skb->tstamp;
203 if (frag_type == LOWPAN_DISPATCH_FRAG1) {
204 /* Calculate uncomp. 6lowpan header to estimate full size */
205 fq->q.meat += lowpan_uncompress_size(skb, NULL);
06aa8b8a 206 fq->q.flags |= INET_FRAG_FIRST_IN;
7240cdec
AA
207 } else {
208 fq->q.meat += skb->len;
209 }
210 add_frag_mem_limit(&fq->q, skb->truesize);
211
06aa8b8a 212 if (fq->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
7240cdec
AA
213 fq->q.meat == fq->q.len) {
214 int res;
215 unsigned long orefdst = skb->_skb_refdst;
216
217 skb->_skb_refdst = 0UL;
218 res = lowpan_frag_reasm(fq, prev, dev);
219 skb->_skb_refdst = orefdst;
220 return res;
221 }
222
7240cdec
AA
223 return -1;
224err:
225 kfree_skb(skb);
226 return -1;
227}
228
229/* Check if this packet is complete.
230 * Returns NULL on failure by any reason, and pointer
231 * to current nexthdr field in reassembled frame.
232 *
233 * It is called with locked fq, and caller must check that
234 * queue is eligible for reassembly i.e. it is not COMPLETE,
235 * the last and the first frames arrived and all the bits are here.
236 */
237static int lowpan_frag_reasm(struct lowpan_frag_queue *fq, struct sk_buff *prev,
238 struct net_device *dev)
239{
240 struct sk_buff *fp, *head = fq->q.fragments;
241 int sum_truesize;
242
243 inet_frag_kill(&fq->q, &lowpan_frags);
244
245 /* Make the one we just received the head. */
246 if (prev) {
247 head = prev->next;
248 fp = skb_clone(head, GFP_ATOMIC);
249
250 if (!fp)
251 goto out_oom;
252
253 fp->next = head->next;
254 if (!fp->next)
255 fq->q.fragments_tail = fp;
256 prev->next = fp;
257
258 skb_morph(head, fq->q.fragments);
259 head->next = fq->q.fragments->next;
260
261 consume_skb(fq->q.fragments);
262 fq->q.fragments = head;
263 }
264
265 /* Head of list must not be cloned. */
266 if (skb_unclone(head, GFP_ATOMIC))
267 goto out_oom;
268
269 /* If the first fragment is fragmented itself, we split
270 * it to two chunks: the first with data and paged part
271 * and the second, holding only fragments.
272 */
273 if (skb_has_frag_list(head)) {
274 struct sk_buff *clone;
275 int i, plen = 0;
276
277 clone = alloc_skb(0, GFP_ATOMIC);
278 if (!clone)
279 goto out_oom;
280 clone->next = head->next;
281 head->next = clone;
282 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
283 skb_frag_list_init(head);
284 for (i = 0; i < skb_shinfo(head)->nr_frags; i++)
285 plen += skb_frag_size(&skb_shinfo(head)->frags[i]);
286 clone->len = head->data_len - plen;
287 clone->data_len = clone->len;
288 head->data_len -= clone->len;
289 head->len -= clone->len;
290 add_frag_mem_limit(&fq->q, clone->truesize);
291 }
292
293 WARN_ON(head == NULL);
294
295 sum_truesize = head->truesize;
296 for (fp = head->next; fp;) {
297 bool headstolen;
298 int delta;
299 struct sk_buff *next = fp->next;
300
301 sum_truesize += fp->truesize;
302 if (skb_try_coalesce(head, fp, &headstolen, &delta)) {
303 kfree_skb_partial(fp, headstolen);
304 } else {
305 if (!skb_shinfo(head)->frag_list)
306 skb_shinfo(head)->frag_list = fp;
307 head->data_len += fp->len;
308 head->len += fp->len;
309 head->truesize += fp->truesize;
310 }
311 fp = next;
312 }
313 sub_frag_mem_limit(&fq->q, sum_truesize);
314
315 head->next = NULL;
316 head->dev = dev;
317 head->tstamp = fq->q.stamp;
318
319 fq->q.fragments = NULL;
320 fq->q.fragments_tail = NULL;
321
322 return 1;
323out_oom:
324 net_dbg_ratelimited("lowpan_frag_reasm: no memory for reassembly\n");
325 return -1;
326}
327
328static int lowpan_get_frag_info(struct sk_buff *skb, const u8 frag_type,
a13061ec 329 struct lowpan_frag_info *frag_info)
7240cdec
AA
330{
331 bool fail;
332 u8 pattern = 0, low = 0;
f870b8c6 333 __be16 d_tag = 0;
7240cdec
AA
334
335 fail = lowpan_fetch_skb(skb, &pattern, 1);
336 fail |= lowpan_fetch_skb(skb, &low, 1);
337 frag_info->d_size = (pattern & 7) << 8 | low;
f870b8c6
AA
338 fail |= lowpan_fetch_skb(skb, &d_tag, 2);
339 frag_info->d_tag = ntohs(d_tag);
7240cdec
AA
340
341 if (frag_type == LOWPAN_DISPATCH_FRAGN) {
342 fail |= lowpan_fetch_skb(skb, &frag_info->d_offset, 1);
343 } else {
344 skb_reset_network_header(skb);
345 frag_info->d_offset = 0;
346 }
347
348 if (unlikely(fail))
349 return -EIO;
350
351 return 0;
352}
353
354int lowpan_frag_rcv(struct sk_buff *skb, const u8 frag_type)
355{
356 struct lowpan_frag_queue *fq;
357 struct net *net = dev_net(skb->dev);
a13061ec 358 struct lowpan_frag_info *frag_info = lowpan_cb(skb);
ae531b94 359 struct ieee802154_addr source, dest;
7240cdec
AA
360 int err;
361
ae531b94
PB
362 source = mac_cb(skb)->source;
363 dest = mac_cb(skb)->dest;
364
7240cdec
AA
365 err = lowpan_get_frag_info(skb, frag_type, frag_info);
366 if (err < 0)
367 goto err;
368
6697dabe
MT
369 if (frag_info->d_size > IPV6_MIN_MTU) {
370 net_warn_ratelimited("lowpan_frag_rcv: datagram size exceeds MTU\n");
7240cdec 371 goto err;
6697dabe 372 }
7240cdec 373
ae531b94 374 fq = fq_find(net, frag_info, &source, &dest);
7240cdec
AA
375 if (fq != NULL) {
376 int ret;
4710d806 377
7240cdec
AA
378 spin_lock(&fq->q.lock);
379 ret = lowpan_frag_queue(fq, skb, frag_type);
380 spin_unlock(&fq->q.lock);
381
382 inet_frag_put(&fq->q, &lowpan_frags);
383 return ret;
384 }
385
386err:
387 kfree_skb(skb);
388 return -1;
389}
390EXPORT_SYMBOL(lowpan_frag_rcv);
391
392#ifdef CONFIG_SYSCTL
1bab4c75
NA
393static int zero;
394
7240cdec
AA
395static struct ctl_table lowpan_frags_ns_ctl_table[] = {
396 {
397 .procname = "6lowpanfrag_high_thresh",
398 .data = &init_net.ieee802154_lowpan.frags.high_thresh,
399 .maxlen = sizeof(int),
400 .mode = 0644,
1bab4c75
NA
401 .proc_handler = proc_dointvec_minmax,
402 .extra1 = &init_net.ieee802154_lowpan.frags.low_thresh
7240cdec
AA
403 },
404 {
405 .procname = "6lowpanfrag_low_thresh",
406 .data = &init_net.ieee802154_lowpan.frags.low_thresh,
407 .maxlen = sizeof(int),
408 .mode = 0644,
1bab4c75
NA
409 .proc_handler = proc_dointvec_minmax,
410 .extra1 = &zero,
411 .extra2 = &init_net.ieee802154_lowpan.frags.high_thresh
7240cdec
AA
412 },
413 {
414 .procname = "6lowpanfrag_time",
415 .data = &init_net.ieee802154_lowpan.frags.timeout,
416 .maxlen = sizeof(int),
417 .mode = 0644,
418 .proc_handler = proc_dointvec_jiffies,
419 },
7240cdec
AA
420 { }
421};
422
e3a57d18
FW
423/* secret interval has been deprecated */
424static int lowpan_frags_secret_interval_unused;
7240cdec
AA
425static struct ctl_table lowpan_frags_ctl_table[] = {
426 {
427 .procname = "6lowpanfrag_secret_interval",
e3a57d18 428 .data = &lowpan_frags_secret_interval_unused,
7240cdec
AA
429 .maxlen = sizeof(int),
430 .mode = 0644,
431 .proc_handler = proc_dointvec_jiffies,
432 },
433 { }
434};
435
436static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
437{
438 struct ctl_table *table;
439 struct ctl_table_header *hdr;
599018a7
LR
440 struct netns_ieee802154_lowpan *ieee802154_lowpan =
441 net_ieee802154_lowpan(net);
7240cdec
AA
442
443 table = lowpan_frags_ns_ctl_table;
444 if (!net_eq(net, &init_net)) {
445 table = kmemdup(table, sizeof(lowpan_frags_ns_ctl_table),
446 GFP_KERNEL);
447 if (table == NULL)
448 goto err_alloc;
449
599018a7 450 table[0].data = &ieee802154_lowpan->frags.high_thresh;
1bab4c75
NA
451 table[0].extra1 = &ieee802154_lowpan->frags.low_thresh;
452 table[0].extra2 = &init_net.ieee802154_lowpan.frags.high_thresh;
599018a7 453 table[1].data = &ieee802154_lowpan->frags.low_thresh;
1bab4c75 454 table[1].extra2 = &ieee802154_lowpan->frags.high_thresh;
599018a7 455 table[2].data = &ieee802154_lowpan->frags.timeout;
7240cdec
AA
456
457 /* Don't export sysctls to unprivileged users */
458 if (net->user_ns != &init_user_ns)
459 table[0].procname = NULL;
460 }
461
462 hdr = register_net_sysctl(net, "net/ieee802154/6lowpan", table);
463 if (hdr == NULL)
464 goto err_reg;
465
599018a7 466 ieee802154_lowpan->sysctl.frags_hdr = hdr;
7240cdec
AA
467 return 0;
468
469err_reg:
470 if (!net_eq(net, &init_net))
471 kfree(table);
472err_alloc:
473 return -ENOMEM;
474}
475
476static void __net_exit lowpan_frags_ns_sysctl_unregister(struct net *net)
477{
478 struct ctl_table *table;
599018a7
LR
479 struct netns_ieee802154_lowpan *ieee802154_lowpan =
480 net_ieee802154_lowpan(net);
7240cdec 481
599018a7
LR
482 table = ieee802154_lowpan->sysctl.frags_hdr->ctl_table_arg;
483 unregister_net_sysctl_table(ieee802154_lowpan->sysctl.frags_hdr);
7240cdec
AA
484 if (!net_eq(net, &init_net))
485 kfree(table);
486}
487
488static struct ctl_table_header *lowpan_ctl_header;
489
3243acd3 490static int __init lowpan_frags_sysctl_register(void)
7240cdec
AA
491{
492 lowpan_ctl_header = register_net_sysctl(&init_net,
493 "net/ieee802154/6lowpan",
494 lowpan_frags_ctl_table);
495 return lowpan_ctl_header == NULL ? -ENOMEM : 0;
496}
497
498static void lowpan_frags_sysctl_unregister(void)
499{
500 unregister_net_sysctl_table(lowpan_ctl_header);
501}
502#else
f0a0c1ce 503static inline int lowpan_frags_ns_sysctl_register(struct net *net)
7240cdec
AA
504{
505 return 0;
506}
507
508static inline void lowpan_frags_ns_sysctl_unregister(struct net *net)
509{
510}
511
f0a0c1ce 512static inline int __init lowpan_frags_sysctl_register(void)
7240cdec
AA
513{
514 return 0;
515}
516
517static inline void lowpan_frags_sysctl_unregister(void)
518{
519}
520#endif
521
522static int __net_init lowpan_frags_init_net(struct net *net)
523{
599018a7
LR
524 struct netns_ieee802154_lowpan *ieee802154_lowpan =
525 net_ieee802154_lowpan(net);
7240cdec 526
599018a7
LR
527 ieee802154_lowpan->frags.high_thresh = IPV6_FRAG_HIGH_THRESH;
528 ieee802154_lowpan->frags.low_thresh = IPV6_FRAG_LOW_THRESH;
529 ieee802154_lowpan->frags.timeout = IPV6_FRAG_TIMEOUT;
599018a7
LR
530
531 inet_frags_init_net(&ieee802154_lowpan->frags);
7240cdec
AA
532
533 return lowpan_frags_ns_sysctl_register(net);
534}
535
536static void __net_exit lowpan_frags_exit_net(struct net *net)
537{
599018a7
LR
538 struct netns_ieee802154_lowpan *ieee802154_lowpan =
539 net_ieee802154_lowpan(net);
540
7240cdec 541 lowpan_frags_ns_sysctl_unregister(net);
599018a7 542 inet_frags_exit_net(&ieee802154_lowpan->frags, &lowpan_frags);
7240cdec
AA
543}
544
545static struct pernet_operations lowpan_frags_ops = {
546 .init = lowpan_frags_init_net,
547 .exit = lowpan_frags_exit_net,
548};
549
550int __init lowpan_net_frag_init(void)
551{
552 int ret;
553
554 ret = lowpan_frags_sysctl_register();
555 if (ret)
37147652 556 return ret;
7240cdec
AA
557
558 ret = register_pernet_subsys(&lowpan_frags_ops);
559 if (ret)
560 goto err_pernet;
561
562 lowpan_frags.hashfn = lowpan_hashfn;
563 lowpan_frags.constructor = lowpan_frag_init;
564 lowpan_frags.destructor = NULL;
565 lowpan_frags.skb_free = NULL;
566 lowpan_frags.qsize = sizeof(struct frag_queue);
567 lowpan_frags.match = lowpan_frag_match;
568 lowpan_frags.frag_expire = lowpan_frag_expire;
d4ad4d22
NA
569 lowpan_frags.frags_cache_name = lowpan_frags_cache_name;
570 ret = inet_frags_init(&lowpan_frags);
571 if (ret)
572 goto err_pernet;
37147652
AA
573
574 return ret;
7240cdec
AA
575err_pernet:
576 lowpan_frags_sysctl_unregister();
7240cdec
AA
577 return ret;
578}
579
580void lowpan_net_frag_exit(void)
581{
582 inet_frags_fini(&lowpan_frags);
583 lowpan_frags_sysctl_unregister();
584 unregister_pernet_subsys(&lowpan_frags_ops);
585}