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>
28 #include <net/ipv6_frag.h>
29 #include <net/inet_frag.h>
31 #include "6lowpan_i.h"
33 static const char lowpan_frags_cache_name[] = "lowpan-frags";
35 static struct inet_frags lowpan_frags;
37 static int lowpan_frag_reasm(struct lowpan_frag_queue *fq,
38 struct sk_buff *prev, struct net_device *ldev);
40 static void lowpan_frag_init(struct inet_frag_queue *q, const void *a)
42 const struct frag_lowpan_compare_key *key = a;
44 BUILD_BUG_ON(sizeof(*key) > sizeof(q->key));
45 memcpy(&q->key, key, sizeof(*key));
48 static void lowpan_frag_expire(struct timer_list *t)
50 struct inet_frag_queue *frag = from_timer(frag, t, timer);
51 struct frag_queue *fq;
53 fq = container_of(frag, struct frag_queue, q);
55 spin_lock(&fq->q.lock);
57 if (fq->q.flags & INET_FRAG_COMPLETE)
60 inet_frag_kill(&fq->q);
62 spin_unlock(&fq->q.lock);
63 inet_frag_put(&fq->q);
66 static inline struct lowpan_frag_queue *
67 fq_find(struct net *net, const struct lowpan_802154_cb *cb,
68 const struct ieee802154_addr *src,
69 const struct ieee802154_addr *dst)
71 struct netns_ieee802154_lowpan *ieee802154_lowpan =
72 net_ieee802154_lowpan(net);
73 struct frag_lowpan_compare_key key = {};
74 struct inet_frag_queue *q;
77 key.d_size = cb->d_size;
81 q = inet_frag_find(&ieee802154_lowpan->frags, &key);
85 return container_of(q, struct lowpan_frag_queue, q);
88 static int lowpan_frag_queue(struct lowpan_frag_queue *fq,
89 struct sk_buff *skb, u8 frag_type)
91 struct sk_buff *prev, *next;
92 struct net_device *ldev;
95 if (fq->q.flags & INET_FRAG_COMPLETE)
98 offset = lowpan_802154_cb(skb)->d_offset << 3;
99 end = lowpan_802154_cb(skb)->d_size;
101 /* Is this the final fragment? */
102 if (offset + skb->len == end) {
103 /* If we already have some bits beyond end
104 * or have different end, the segment is corrupted.
106 if (end < fq->q.len ||
107 ((fq->q.flags & INET_FRAG_LAST_IN) && end != fq->q.len))
109 fq->q.flags |= INET_FRAG_LAST_IN;
112 if (end > fq->q.len) {
113 /* Some bits beyond end -> corruption. */
114 if (fq->q.flags & INET_FRAG_LAST_IN)
120 /* Find out which fragments are in front and at the back of us
121 * in the chain of fragments so far. We must know where to put
122 * this fragment, right?
124 prev = fq->q.fragments_tail;
126 lowpan_802154_cb(prev)->d_offset <
127 lowpan_802154_cb(skb)->d_offset) {
132 for (next = fq->q.fragments; next != NULL; next = next->next) {
133 if (lowpan_802154_cb(next)->d_offset >=
134 lowpan_802154_cb(skb)->d_offset)
140 /* Insert this fragment in the chain of fragments. */
143 fq->q.fragments_tail = skb;
147 fq->q.fragments = skb;
153 fq->q.stamp = skb->tstamp;
154 if (frag_type == LOWPAN_DISPATCH_FRAG1)
155 fq->q.flags |= INET_FRAG_FIRST_IN;
157 fq->q.meat += skb->len;
158 add_frag_mem_limit(fq->q.net, skb->truesize);
160 if (fq->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
161 fq->q.meat == fq->q.len) {
163 unsigned long orefdst = skb->_skb_refdst;
165 skb->_skb_refdst = 0UL;
166 res = lowpan_frag_reasm(fq, prev, ldev);
167 skb->_skb_refdst = orefdst;
177 /* Check if this packet is complete.
178 * Returns NULL on failure by any reason, and pointer
179 * to current nexthdr field in reassembled frame.
181 * It is called with locked fq, and caller must check that
182 * queue is eligible for reassembly i.e. it is not COMPLETE,
183 * the last and the first frames arrived and all the bits are here.
185 static int lowpan_frag_reasm(struct lowpan_frag_queue *fq, struct sk_buff *prev,
186 struct net_device *ldev)
188 struct sk_buff *fp, *head = fq->q.fragments;
191 inet_frag_kill(&fq->q);
193 /* Make the one we just received the head. */
196 fp = skb_clone(head, GFP_ATOMIC);
201 fp->next = head->next;
203 fq->q.fragments_tail = fp;
206 skb_morph(head, fq->q.fragments);
207 head->next = fq->q.fragments->next;
209 consume_skb(fq->q.fragments);
210 fq->q.fragments = head;
213 /* Head of list must not be cloned. */
214 if (skb_unclone(head, GFP_ATOMIC))
217 /* If the first fragment is fragmented itself, we split
218 * it to two chunks: the first with data and paged part
219 * and the second, holding only fragments.
221 if (skb_has_frag_list(head)) {
222 struct sk_buff *clone;
225 clone = alloc_skb(0, GFP_ATOMIC);
228 clone->next = head->next;
230 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
231 skb_frag_list_init(head);
232 for (i = 0; i < skb_shinfo(head)->nr_frags; i++)
233 plen += skb_frag_size(&skb_shinfo(head)->frags[i]);
234 clone->len = head->data_len - plen;
235 clone->data_len = clone->len;
236 head->data_len -= clone->len;
237 head->len -= clone->len;
238 add_frag_mem_limit(fq->q.net, clone->truesize);
241 WARN_ON(head == NULL);
243 sum_truesize = head->truesize;
244 for (fp = head->next; fp;) {
247 struct sk_buff *next = fp->next;
249 sum_truesize += fp->truesize;
250 if (skb_try_coalesce(head, fp, &headstolen, &delta)) {
251 kfree_skb_partial(fp, headstolen);
253 if (!skb_shinfo(head)->frag_list)
254 skb_shinfo(head)->frag_list = fp;
255 head->data_len += fp->len;
256 head->len += fp->len;
257 head->truesize += fp->truesize;
261 sub_frag_mem_limit(fq->q.net, sum_truesize);
265 head->tstamp = fq->q.stamp;
267 fq->q.fragments = NULL;
268 fq->q.fragments_tail = NULL;
272 net_dbg_ratelimited("lowpan_frag_reasm: no memory for reassembly\n");
276 static int lowpan_frag_rx_handlers_result(struct sk_buff *skb,
277 lowpan_rx_result res)
281 return NET_RX_SUCCESS;
283 /* nobody cared about this packet */
284 net_warn_ratelimited("%s: received unknown dispatch\n",
289 /* all others failure */
294 static lowpan_rx_result lowpan_frag_rx_h_iphc(struct sk_buff *skb)
298 if (!lowpan_is_iphc(*skb_network_header(skb)))
301 ret = lowpan_iphc_decompress(skb);
308 static int lowpan_invoke_frag_rx_handlers(struct sk_buff *skb)
310 lowpan_rx_result res;
312 #define CALL_RXH(rxh) \
315 if (res != RX_CONTINUE) \
319 /* likely at first */
320 CALL_RXH(lowpan_frag_rx_h_iphc);
321 CALL_RXH(lowpan_rx_h_ipv6);
324 return lowpan_frag_rx_handlers_result(skb, res);
328 #define LOWPAN_FRAG_DGRAM_SIZE_HIGH_MASK 0x07
329 #define LOWPAN_FRAG_DGRAM_SIZE_HIGH_SHIFT 8
331 static int lowpan_get_cb(struct sk_buff *skb, u8 frag_type,
332 struct lowpan_802154_cb *cb)
335 u8 high = 0, low = 0;
338 fail = lowpan_fetch_skb(skb, &high, 1);
339 fail |= lowpan_fetch_skb(skb, &low, 1);
340 /* remove the dispatch value and use first three bits as high value
341 * for the datagram size
343 cb->d_size = (high & LOWPAN_FRAG_DGRAM_SIZE_HIGH_MASK) <<
344 LOWPAN_FRAG_DGRAM_SIZE_HIGH_SHIFT | low;
345 fail |= lowpan_fetch_skb(skb, &d_tag, 2);
346 cb->d_tag = ntohs(d_tag);
348 if (frag_type == LOWPAN_DISPATCH_FRAGN) {
349 fail |= lowpan_fetch_skb(skb, &cb->d_offset, 1);
351 skb_reset_network_header(skb);
353 /* check if datagram_size has ipv6hdr on FRAG1 */
354 fail |= cb->d_size < sizeof(struct ipv6hdr);
355 /* check if we can dereference the dispatch value */
365 int lowpan_frag_rcv(struct sk_buff *skb, u8 frag_type)
367 struct lowpan_frag_queue *fq;
368 struct net *net = dev_net(skb->dev);
369 struct lowpan_802154_cb *cb = lowpan_802154_cb(skb);
370 struct ieee802154_hdr hdr = {};
373 if (ieee802154_hdr_peek_addrs(skb, &hdr) < 0)
376 err = lowpan_get_cb(skb, frag_type, cb);
380 if (frag_type == LOWPAN_DISPATCH_FRAG1) {
381 err = lowpan_invoke_frag_rx_handlers(skb);
382 if (err == NET_RX_DROP)
386 if (cb->d_size > IPV6_MIN_MTU) {
387 net_warn_ratelimited("lowpan_frag_rcv: datagram size exceeds MTU\n");
391 fq = fq_find(net, cb, &hdr.source, &hdr.dest);
395 spin_lock(&fq->q.lock);
396 ret = lowpan_frag_queue(fq, skb, frag_type);
397 spin_unlock(&fq->q.lock);
399 inet_frag_put(&fq->q);
410 static struct ctl_table lowpan_frags_ns_ctl_table[] = {
412 .procname = "6lowpanfrag_high_thresh",
413 .data = &init_net.ieee802154_lowpan.frags.high_thresh,
414 .maxlen = sizeof(unsigned long),
416 .proc_handler = proc_doulongvec_minmax,
417 .extra1 = &init_net.ieee802154_lowpan.frags.low_thresh
420 .procname = "6lowpanfrag_low_thresh",
421 .data = &init_net.ieee802154_lowpan.frags.low_thresh,
422 .maxlen = sizeof(unsigned long),
424 .proc_handler = proc_doulongvec_minmax,
425 .extra2 = &init_net.ieee802154_lowpan.frags.high_thresh
428 .procname = "6lowpanfrag_time",
429 .data = &init_net.ieee802154_lowpan.frags.timeout,
430 .maxlen = sizeof(int),
432 .proc_handler = proc_dointvec_jiffies,
437 /* secret interval has been deprecated */
438 static int lowpan_frags_secret_interval_unused;
439 static struct ctl_table lowpan_frags_ctl_table[] = {
441 .procname = "6lowpanfrag_secret_interval",
442 .data = &lowpan_frags_secret_interval_unused,
443 .maxlen = sizeof(int),
445 .proc_handler = proc_dointvec_jiffies,
450 static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
452 struct ctl_table *table;
453 struct ctl_table_header *hdr;
454 struct netns_ieee802154_lowpan *ieee802154_lowpan =
455 net_ieee802154_lowpan(net);
457 table = lowpan_frags_ns_ctl_table;
458 if (!net_eq(net, &init_net)) {
459 table = kmemdup(table, sizeof(lowpan_frags_ns_ctl_table),
464 table[0].data = &ieee802154_lowpan->frags.high_thresh;
465 table[0].extra1 = &ieee802154_lowpan->frags.low_thresh;
466 table[0].extra2 = &init_net.ieee802154_lowpan.frags.high_thresh;
467 table[1].data = &ieee802154_lowpan->frags.low_thresh;
468 table[1].extra2 = &ieee802154_lowpan->frags.high_thresh;
469 table[2].data = &ieee802154_lowpan->frags.timeout;
471 /* Don't export sysctls to unprivileged users */
472 if (net->user_ns != &init_user_ns)
473 table[0].procname = NULL;
476 hdr = register_net_sysctl(net, "net/ieee802154/6lowpan", table);
480 ieee802154_lowpan->sysctl.frags_hdr = hdr;
484 if (!net_eq(net, &init_net))
490 static void __net_exit lowpan_frags_ns_sysctl_unregister(struct net *net)
492 struct ctl_table *table;
493 struct netns_ieee802154_lowpan *ieee802154_lowpan =
494 net_ieee802154_lowpan(net);
496 table = ieee802154_lowpan->sysctl.frags_hdr->ctl_table_arg;
497 unregister_net_sysctl_table(ieee802154_lowpan->sysctl.frags_hdr);
498 if (!net_eq(net, &init_net))
502 static struct ctl_table_header *lowpan_ctl_header;
504 static int __init lowpan_frags_sysctl_register(void)
506 lowpan_ctl_header = register_net_sysctl(&init_net,
507 "net/ieee802154/6lowpan",
508 lowpan_frags_ctl_table);
509 return lowpan_ctl_header == NULL ? -ENOMEM : 0;
512 static void lowpan_frags_sysctl_unregister(void)
514 unregister_net_sysctl_table(lowpan_ctl_header);
517 static inline int lowpan_frags_ns_sysctl_register(struct net *net)
522 static inline void lowpan_frags_ns_sysctl_unregister(struct net *net)
526 static inline int __init lowpan_frags_sysctl_register(void)
531 static inline void lowpan_frags_sysctl_unregister(void)
536 static int __net_init lowpan_frags_init_net(struct net *net)
538 struct netns_ieee802154_lowpan *ieee802154_lowpan =
539 net_ieee802154_lowpan(net);
542 ieee802154_lowpan->frags.high_thresh = IPV6_FRAG_HIGH_THRESH;
543 ieee802154_lowpan->frags.low_thresh = IPV6_FRAG_LOW_THRESH;
544 ieee802154_lowpan->frags.timeout = IPV6_FRAG_TIMEOUT;
545 ieee802154_lowpan->frags.f = &lowpan_frags;
547 res = inet_frags_init_net(&ieee802154_lowpan->frags);
550 res = lowpan_frags_ns_sysctl_register(net);
552 inet_frags_exit_net(&ieee802154_lowpan->frags);
556 static void __net_exit lowpan_frags_exit_net(struct net *net)
558 struct netns_ieee802154_lowpan *ieee802154_lowpan =
559 net_ieee802154_lowpan(net);
561 lowpan_frags_ns_sysctl_unregister(net);
562 inet_frags_exit_net(&ieee802154_lowpan->frags);
565 static struct pernet_operations lowpan_frags_ops = {
566 .init = lowpan_frags_init_net,
567 .exit = lowpan_frags_exit_net,
570 static u32 lowpan_key_hashfn(const void *data, u32 len, u32 seed)
573 sizeof(struct frag_lowpan_compare_key) / sizeof(u32), seed);
576 static u32 lowpan_obj_hashfn(const void *data, u32 len, u32 seed)
578 const struct inet_frag_queue *fq = data;
580 return jhash2((const u32 *)&fq->key,
581 sizeof(struct frag_lowpan_compare_key) / sizeof(u32), seed);
584 static int lowpan_obj_cmpfn(struct rhashtable_compare_arg *arg, const void *ptr)
586 const struct frag_lowpan_compare_key *key = arg->key;
587 const struct inet_frag_queue *fq = ptr;
589 return !!memcmp(&fq->key, key, sizeof(*key));
592 static const struct rhashtable_params lowpan_rhash_params = {
593 .head_offset = offsetof(struct inet_frag_queue, node),
594 .hashfn = lowpan_key_hashfn,
595 .obj_hashfn = lowpan_obj_hashfn,
596 .obj_cmpfn = lowpan_obj_cmpfn,
597 .automatic_shrinking = true,
600 int __init lowpan_net_frag_init(void)
604 lowpan_frags.constructor = lowpan_frag_init;
605 lowpan_frags.destructor = NULL;
606 lowpan_frags.qsize = sizeof(struct frag_queue);
607 lowpan_frags.frag_expire = lowpan_frag_expire;
608 lowpan_frags.frags_cache_name = lowpan_frags_cache_name;
609 lowpan_frags.rhash_params = lowpan_rhash_params;
610 ret = inet_frags_init(&lowpan_frags);
614 ret = lowpan_frags_sysctl_register();
618 ret = register_pernet_subsys(&lowpan_frags_ops);
624 lowpan_frags_sysctl_unregister();
626 inet_frags_fini(&lowpan_frags);
630 void lowpan_net_frag_exit(void)
632 lowpan_frags_sysctl_unregister();
633 unregister_pernet_subsys(&lowpan_frags_ops);
634 inet_frags_fini(&lowpan_frags);