1 /* 6LoWPAN fragment reassembly
5 * Alexander Aring <aar@pengutronix.de>
7 * Based on: net/ipv6/reassembly.c
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.
15 #define pr_fmt(fmt) "6LoWPAN: " fmt
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>
26 #include <net/ieee802154_netdev.h>
27 #include <net/6lowpan.h>
29 #include <net/inet_frag.h>
31 #include "reassembly.h"
33 static const char lowpan_frags_cache_name[] = "lowpan-frags";
35 struct lowpan_frag_info {
41 static struct lowpan_frag_info *lowpan_cb(struct sk_buff *skb)
43 return (struct lowpan_frag_info *)skb->cb;
46 static struct inet_frags lowpan_frags;
48 static int lowpan_frag_reasm(struct lowpan_frag_queue *fq,
49 struct sk_buff *prev, struct net_device *dev);
51 static unsigned int lowpan_hash_frag(__be16 tag, u16 d_size,
52 const struct ieee802154_addr *saddr,
53 const struct ieee802154_addr *daddr)
55 net_get_random_once(&lowpan_frags.rnd, sizeof(lowpan_frags.rnd));
56 return jhash_3words(ieee802154_addr_hash(saddr),
57 ieee802154_addr_hash(daddr),
58 (__force u32)(tag + (d_size << 16)),
62 static unsigned int lowpan_hashfn(const struct inet_frag_queue *q)
64 const struct lowpan_frag_queue *fq;
66 fq = container_of(q, struct lowpan_frag_queue, q);
67 return lowpan_hash_frag(fq->tag, fq->d_size, &fq->saddr, &fq->daddr);
70 static bool lowpan_frag_match(const struct inet_frag_queue *q, const void *a)
72 const struct lowpan_frag_queue *fq;
73 const struct lowpan_create_arg *arg = a;
75 fq = container_of(q, struct lowpan_frag_queue, q);
76 return fq->tag == arg->tag && fq->d_size == arg->d_size &&
77 ieee802154_addr_equal(&fq->saddr, arg->src) &&
78 ieee802154_addr_equal(&fq->daddr, arg->dst);
81 static void lowpan_frag_init(struct inet_frag_queue *q, const void *a)
83 const struct lowpan_create_arg *arg = a;
84 struct lowpan_frag_queue *fq;
86 fq = container_of(q, struct lowpan_frag_queue, q);
89 fq->d_size = arg->d_size;
90 fq->saddr = *arg->src;
91 fq->daddr = *arg->dst;
94 static void lowpan_frag_expire(unsigned long data)
96 struct frag_queue *fq;
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);
102 spin_lock(&fq->q.lock);
104 if (fq->q.flags & INET_FRAG_COMPLETE)
107 inet_frag_kill(&fq->q, &lowpan_frags);
109 spin_unlock(&fq->q.lock);
110 inet_frag_put(&fq->q, &lowpan_frags);
113 static inline struct lowpan_frag_queue *
114 fq_find(struct net *net, const struct lowpan_frag_info *frag_info,
115 const struct ieee802154_addr *src,
116 const struct ieee802154_addr *dst)
118 struct inet_frag_queue *q;
119 struct lowpan_create_arg arg;
121 struct netns_ieee802154_lowpan *ieee802154_lowpan =
122 net_ieee802154_lowpan(net);
124 arg.tag = frag_info->d_tag;
125 arg.d_size = frag_info->d_size;
129 hash = lowpan_hash_frag(frag_info->d_tag, frag_info->d_size, src, dst);
131 q = inet_frag_find(&ieee802154_lowpan->frags,
132 &lowpan_frags, &arg, hash);
133 if (IS_ERR_OR_NULL(q)) {
134 inet_frag_maybe_warn_overflow(q, pr_fmt());
137 return container_of(q, struct lowpan_frag_queue, q);
140 static int lowpan_frag_queue(struct lowpan_frag_queue *fq,
141 struct sk_buff *skb, const u8 frag_type)
143 struct sk_buff *prev, *next;
144 struct net_device *dev;
147 if (fq->q.flags & INET_FRAG_COMPLETE)
150 offset = lowpan_cb(skb)->d_offset << 3;
151 end = lowpan_cb(skb)->d_size;
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.
158 if (end < fq->q.len ||
159 ((fq->q.flags & INET_FRAG_LAST_IN) && end != fq->q.len))
161 fq->q.flags |= INET_FRAG_LAST_IN;
164 if (end > fq->q.len) {
165 /* Some bits beyond end -> corruption. */
166 if (fq->q.flags & INET_FRAG_LAST_IN)
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?
176 prev = fq->q.fragments_tail;
177 if (!prev || lowpan_cb(prev)->d_offset < lowpan_cb(skb)->d_offset) {
182 for (next = fq->q.fragments; next != NULL; next = next->next) {
183 if (lowpan_cb(next)->d_offset >= lowpan_cb(skb)->d_offset)
189 /* Insert this fragment in the chain of fragments. */
192 fq->q.fragments_tail = skb;
196 fq->q.fragments = skb;
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);
206 fq->q.flags |= INET_FRAG_FIRST_IN;
208 fq->q.meat += skb->len;
210 add_frag_mem_limit(&fq->q, skb->truesize);
212 if (fq->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
213 fq->q.meat == fq->q.len) {
215 unsigned long orefdst = skb->_skb_refdst;
217 skb->_skb_refdst = 0UL;
218 res = lowpan_frag_reasm(fq, prev, dev);
219 skb->_skb_refdst = orefdst;
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.
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.
237 static int lowpan_frag_reasm(struct lowpan_frag_queue *fq, struct sk_buff *prev,
238 struct net_device *dev)
240 struct sk_buff *fp, *head = fq->q.fragments;
243 inet_frag_kill(&fq->q, &lowpan_frags);
245 /* Make the one we just received the head. */
248 fp = skb_clone(head, GFP_ATOMIC);
253 fp->next = head->next;
255 fq->q.fragments_tail = fp;
258 skb_morph(head, fq->q.fragments);
259 head->next = fq->q.fragments->next;
261 consume_skb(fq->q.fragments);
262 fq->q.fragments = head;
265 /* Head of list must not be cloned. */
266 if (skb_unclone(head, GFP_ATOMIC))
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.
273 if (skb_has_frag_list(head)) {
274 struct sk_buff *clone;
277 clone = alloc_skb(0, GFP_ATOMIC);
280 clone->next = head->next;
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);
293 WARN_ON(head == NULL);
295 sum_truesize = head->truesize;
296 for (fp = head->next; fp;) {
299 struct sk_buff *next = fp->next;
301 sum_truesize += fp->truesize;
302 if (skb_try_coalesce(head, fp, &headstolen, &delta)) {
303 kfree_skb_partial(fp, headstolen);
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;
313 sub_frag_mem_limit(&fq->q, sum_truesize);
317 head->tstamp = fq->q.stamp;
319 fq->q.fragments = NULL;
320 fq->q.fragments_tail = NULL;
324 net_dbg_ratelimited("lowpan_frag_reasm: no memory for reassembly\n");
328 static int lowpan_get_frag_info(struct sk_buff *skb, const u8 frag_type,
329 struct lowpan_frag_info *frag_info)
332 u8 pattern = 0, low = 0;
334 fail = lowpan_fetch_skb(skb, &pattern, 1);
335 fail |= lowpan_fetch_skb(skb, &low, 1);
336 frag_info->d_size = (pattern & 7) << 8 | low;
337 fail |= lowpan_fetch_skb(skb, &frag_info->d_tag, 2);
339 if (frag_type == LOWPAN_DISPATCH_FRAGN) {
340 fail |= lowpan_fetch_skb(skb, &frag_info->d_offset, 1);
342 skb_reset_network_header(skb);
343 frag_info->d_offset = 0;
352 int lowpan_frag_rcv(struct sk_buff *skb, const u8 frag_type)
354 struct lowpan_frag_queue *fq;
355 struct net *net = dev_net(skb->dev);
356 struct lowpan_frag_info *frag_info = lowpan_cb(skb);
357 struct ieee802154_addr source, dest;
358 struct netns_ieee802154_lowpan *ieee802154_lowpan =
359 net_ieee802154_lowpan(net);
362 source = mac_cb(skb)->source;
363 dest = mac_cb(skb)->dest;
365 err = lowpan_get_frag_info(skb, frag_type, frag_info);
369 if (frag_info->d_size > ieee802154_lowpan->max_dsize)
372 fq = fq_find(net, frag_info, &source, &dest);
376 spin_lock(&fq->q.lock);
377 ret = lowpan_frag_queue(fq, skb, frag_type);
378 spin_unlock(&fq->q.lock);
380 inet_frag_put(&fq->q, &lowpan_frags);
388 EXPORT_SYMBOL(lowpan_frag_rcv);
393 static struct ctl_table lowpan_frags_ns_ctl_table[] = {
395 .procname = "6lowpanfrag_high_thresh",
396 .data = &init_net.ieee802154_lowpan.frags.high_thresh,
397 .maxlen = sizeof(int),
399 .proc_handler = proc_dointvec_minmax,
400 .extra1 = &init_net.ieee802154_lowpan.frags.low_thresh
403 .procname = "6lowpanfrag_low_thresh",
404 .data = &init_net.ieee802154_lowpan.frags.low_thresh,
405 .maxlen = sizeof(int),
407 .proc_handler = proc_dointvec_minmax,
409 .extra2 = &init_net.ieee802154_lowpan.frags.high_thresh
412 .procname = "6lowpanfrag_time",
413 .data = &init_net.ieee802154_lowpan.frags.timeout,
414 .maxlen = sizeof(int),
416 .proc_handler = proc_dointvec_jiffies,
419 .procname = "6lowpanfrag_max_datagram_size",
420 .data = &init_net.ieee802154_lowpan.max_dsize,
421 .maxlen = sizeof(int),
423 .proc_handler = proc_dointvec
428 /* secret interval has been deprecated */
429 static int lowpan_frags_secret_interval_unused;
430 static struct ctl_table lowpan_frags_ctl_table[] = {
432 .procname = "6lowpanfrag_secret_interval",
433 .data = &lowpan_frags_secret_interval_unused,
434 .maxlen = sizeof(int),
436 .proc_handler = proc_dointvec_jiffies,
441 static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
443 struct ctl_table *table;
444 struct ctl_table_header *hdr;
445 struct netns_ieee802154_lowpan *ieee802154_lowpan =
446 net_ieee802154_lowpan(net);
448 table = lowpan_frags_ns_ctl_table;
449 if (!net_eq(net, &init_net)) {
450 table = kmemdup(table, sizeof(lowpan_frags_ns_ctl_table),
455 table[0].data = &ieee802154_lowpan->frags.high_thresh;
456 table[0].extra1 = &ieee802154_lowpan->frags.low_thresh;
457 table[0].extra2 = &init_net.ieee802154_lowpan.frags.high_thresh;
458 table[1].data = &ieee802154_lowpan->frags.low_thresh;
459 table[1].extra2 = &ieee802154_lowpan->frags.high_thresh;
460 table[2].data = &ieee802154_lowpan->frags.timeout;
461 table[3].data = &ieee802154_lowpan->max_dsize;
463 /* Don't export sysctls to unprivileged users */
464 if (net->user_ns != &init_user_ns)
465 table[0].procname = NULL;
468 hdr = register_net_sysctl(net, "net/ieee802154/6lowpan", table);
472 ieee802154_lowpan->sysctl.frags_hdr = hdr;
476 if (!net_eq(net, &init_net))
482 static void __net_exit lowpan_frags_ns_sysctl_unregister(struct net *net)
484 struct ctl_table *table;
485 struct netns_ieee802154_lowpan *ieee802154_lowpan =
486 net_ieee802154_lowpan(net);
488 table = ieee802154_lowpan->sysctl.frags_hdr->ctl_table_arg;
489 unregister_net_sysctl_table(ieee802154_lowpan->sysctl.frags_hdr);
490 if (!net_eq(net, &init_net))
494 static struct ctl_table_header *lowpan_ctl_header;
496 static int lowpan_frags_sysctl_register(void)
498 lowpan_ctl_header = register_net_sysctl(&init_net,
499 "net/ieee802154/6lowpan",
500 lowpan_frags_ctl_table);
501 return lowpan_ctl_header == NULL ? -ENOMEM : 0;
504 static void lowpan_frags_sysctl_unregister(void)
506 unregister_net_sysctl_table(lowpan_ctl_header);
509 static inline int lowpan_frags_ns_sysctl_register(struct net *net)
514 static inline void lowpan_frags_ns_sysctl_unregister(struct net *net)
518 static inline int lowpan_frags_sysctl_register(void)
523 static inline void lowpan_frags_sysctl_unregister(void)
528 static int __net_init lowpan_frags_init_net(struct net *net)
530 struct netns_ieee802154_lowpan *ieee802154_lowpan =
531 net_ieee802154_lowpan(net);
533 ieee802154_lowpan->frags.high_thresh = IPV6_FRAG_HIGH_THRESH;
534 ieee802154_lowpan->frags.low_thresh = IPV6_FRAG_LOW_THRESH;
535 ieee802154_lowpan->frags.timeout = IPV6_FRAG_TIMEOUT;
536 ieee802154_lowpan->max_dsize = 0xFFFF;
538 inet_frags_init_net(&ieee802154_lowpan->frags);
540 return lowpan_frags_ns_sysctl_register(net);
543 static void __net_exit lowpan_frags_exit_net(struct net *net)
545 struct netns_ieee802154_lowpan *ieee802154_lowpan =
546 net_ieee802154_lowpan(net);
548 lowpan_frags_ns_sysctl_unregister(net);
549 inet_frags_exit_net(&ieee802154_lowpan->frags, &lowpan_frags);
552 static struct pernet_operations lowpan_frags_ops = {
553 .init = lowpan_frags_init_net,
554 .exit = lowpan_frags_exit_net,
557 int __init lowpan_net_frag_init(void)
561 ret = lowpan_frags_sysctl_register();
565 ret = register_pernet_subsys(&lowpan_frags_ops);
569 lowpan_frags.hashfn = lowpan_hashfn;
570 lowpan_frags.constructor = lowpan_frag_init;
571 lowpan_frags.destructor = NULL;
572 lowpan_frags.skb_free = NULL;
573 lowpan_frags.qsize = sizeof(struct frag_queue);
574 lowpan_frags.match = lowpan_frag_match;
575 lowpan_frags.frag_expire = lowpan_frag_expire;
576 lowpan_frags.frags_cache_name = lowpan_frags_cache_name;
577 ret = inet_frags_init(&lowpan_frags);
583 lowpan_frags_sysctl_unregister();
587 void lowpan_net_frag_exit(void)
589 inet_frags_fini(&lowpan_frags);
590 lowpan_frags_sysctl_unregister();
591 unregister_pernet_subsys(&lowpan_frags_ops);