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;
43 struct lowpan_frag_queue *fq;
45 fq = container_of(q, struct lowpan_frag_queue, q);
47 BUILD_BUG_ON(sizeof(*key) > sizeof(q->key));
48 memcpy(&q->key, key, sizeof(*key));
51 static void lowpan_frag_expire(struct timer_list *t)
53 struct inet_frag_queue *frag = from_timer(frag, t, timer);
54 struct frag_queue *fq;
57 fq = container_of(frag, struct frag_queue, q);
58 net = container_of(fq->q.net, struct net, ieee802154_lowpan.frags);
60 spin_lock(&fq->q.lock);
62 if (fq->q.flags & INET_FRAG_COMPLETE)
65 inet_frag_kill(&fq->q);
67 spin_unlock(&fq->q.lock);
68 inet_frag_put(&fq->q);
71 static inline struct lowpan_frag_queue *
72 fq_find(struct net *net, const struct lowpan_802154_cb *cb,
73 const struct ieee802154_addr *src,
74 const struct ieee802154_addr *dst)
76 struct netns_ieee802154_lowpan *ieee802154_lowpan =
77 net_ieee802154_lowpan(net);
78 struct frag_lowpan_compare_key key = {};
79 struct inet_frag_queue *q;
82 key.d_size = cb->d_size;
86 q = inet_frag_find(&ieee802154_lowpan->frags, &key);
90 return container_of(q, struct lowpan_frag_queue, q);
93 static int lowpan_frag_queue(struct lowpan_frag_queue *fq,
94 struct sk_buff *skb, u8 frag_type)
96 struct sk_buff *prev, *next;
97 struct net_device *ldev;
100 if (fq->q.flags & INET_FRAG_COMPLETE)
103 offset = lowpan_802154_cb(skb)->d_offset << 3;
104 end = lowpan_802154_cb(skb)->d_size;
106 /* Is this the final fragment? */
107 if (offset + skb->len == end) {
108 /* If we already have some bits beyond end
109 * or have different end, the segment is corrupted.
111 if (end < fq->q.len ||
112 ((fq->q.flags & INET_FRAG_LAST_IN) && end != fq->q.len))
114 fq->q.flags |= INET_FRAG_LAST_IN;
117 if (end > fq->q.len) {
118 /* Some bits beyond end -> corruption. */
119 if (fq->q.flags & INET_FRAG_LAST_IN)
125 /* Find out which fragments are in front and at the back of us
126 * in the chain of fragments so far. We must know where to put
127 * this fragment, right?
129 prev = fq->q.fragments_tail;
131 lowpan_802154_cb(prev)->d_offset <
132 lowpan_802154_cb(skb)->d_offset) {
137 for (next = fq->q.fragments; next != NULL; next = next->next) {
138 if (lowpan_802154_cb(next)->d_offset >=
139 lowpan_802154_cb(skb)->d_offset)
145 /* Insert this fragment in the chain of fragments. */
148 fq->q.fragments_tail = skb;
152 fq->q.fragments = skb;
158 fq->q.stamp = skb->tstamp;
159 if (frag_type == LOWPAN_DISPATCH_FRAG1)
160 fq->q.flags |= INET_FRAG_FIRST_IN;
162 fq->q.meat += skb->len;
163 add_frag_mem_limit(fq->q.net, skb->truesize);
165 if (fq->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
166 fq->q.meat == fq->q.len) {
168 unsigned long orefdst = skb->_skb_refdst;
170 skb->_skb_refdst = 0UL;
171 res = lowpan_frag_reasm(fq, prev, ldev);
172 skb->_skb_refdst = orefdst;
182 /* Check if this packet is complete.
183 * Returns NULL on failure by any reason, and pointer
184 * to current nexthdr field in reassembled frame.
186 * It is called with locked fq, and caller must check that
187 * queue is eligible for reassembly i.e. it is not COMPLETE,
188 * the last and the first frames arrived and all the bits are here.
190 static int lowpan_frag_reasm(struct lowpan_frag_queue *fq, struct sk_buff *prev,
191 struct net_device *ldev)
193 struct sk_buff *fp, *head = fq->q.fragments;
196 inet_frag_kill(&fq->q);
198 /* Make the one we just received the head. */
201 fp = skb_clone(head, GFP_ATOMIC);
206 fp->next = head->next;
208 fq->q.fragments_tail = fp;
211 skb_morph(head, fq->q.fragments);
212 head->next = fq->q.fragments->next;
214 consume_skb(fq->q.fragments);
215 fq->q.fragments = head;
218 /* Head of list must not be cloned. */
219 if (skb_unclone(head, GFP_ATOMIC))
222 /* If the first fragment is fragmented itself, we split
223 * it to two chunks: the first with data and paged part
224 * and the second, holding only fragments.
226 if (skb_has_frag_list(head)) {
227 struct sk_buff *clone;
230 clone = alloc_skb(0, GFP_ATOMIC);
233 clone->next = head->next;
235 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
236 skb_frag_list_init(head);
237 for (i = 0; i < skb_shinfo(head)->nr_frags; i++)
238 plen += skb_frag_size(&skb_shinfo(head)->frags[i]);
239 clone->len = head->data_len - plen;
240 clone->data_len = clone->len;
241 head->data_len -= clone->len;
242 head->len -= clone->len;
243 add_frag_mem_limit(fq->q.net, clone->truesize);
246 WARN_ON(head == NULL);
248 sum_truesize = head->truesize;
249 for (fp = head->next; fp;) {
252 struct sk_buff *next = fp->next;
254 sum_truesize += fp->truesize;
255 if (skb_try_coalesce(head, fp, &headstolen, &delta)) {
256 kfree_skb_partial(fp, headstolen);
258 if (!skb_shinfo(head)->frag_list)
259 skb_shinfo(head)->frag_list = fp;
260 head->data_len += fp->len;
261 head->len += fp->len;
262 head->truesize += fp->truesize;
266 sub_frag_mem_limit(fq->q.net, sum_truesize);
270 head->tstamp = fq->q.stamp;
272 fq->q.fragments = NULL;
273 fq->q.fragments_tail = NULL;
277 net_dbg_ratelimited("lowpan_frag_reasm: no memory for reassembly\n");
281 static int lowpan_frag_rx_handlers_result(struct sk_buff *skb,
282 lowpan_rx_result res)
286 return NET_RX_SUCCESS;
288 /* nobody cared about this packet */
289 net_warn_ratelimited("%s: received unknown dispatch\n",
294 /* all others failure */
299 static lowpan_rx_result lowpan_frag_rx_h_iphc(struct sk_buff *skb)
303 if (!lowpan_is_iphc(*skb_network_header(skb)))
306 ret = lowpan_iphc_decompress(skb);
313 static int lowpan_invoke_frag_rx_handlers(struct sk_buff *skb)
315 lowpan_rx_result res;
317 #define CALL_RXH(rxh) \
320 if (res != RX_CONTINUE) \
324 /* likely at first */
325 CALL_RXH(lowpan_frag_rx_h_iphc);
326 CALL_RXH(lowpan_rx_h_ipv6);
329 return lowpan_frag_rx_handlers_result(skb, res);
333 #define LOWPAN_FRAG_DGRAM_SIZE_HIGH_MASK 0x07
334 #define LOWPAN_FRAG_DGRAM_SIZE_HIGH_SHIFT 8
336 static int lowpan_get_cb(struct sk_buff *skb, u8 frag_type,
337 struct lowpan_802154_cb *cb)
340 u8 high = 0, low = 0;
343 fail = lowpan_fetch_skb(skb, &high, 1);
344 fail |= lowpan_fetch_skb(skb, &low, 1);
345 /* remove the dispatch value and use first three bits as high value
346 * for the datagram size
348 cb->d_size = (high & LOWPAN_FRAG_DGRAM_SIZE_HIGH_MASK) <<
349 LOWPAN_FRAG_DGRAM_SIZE_HIGH_SHIFT | low;
350 fail |= lowpan_fetch_skb(skb, &d_tag, 2);
351 cb->d_tag = ntohs(d_tag);
353 if (frag_type == LOWPAN_DISPATCH_FRAGN) {
354 fail |= lowpan_fetch_skb(skb, &cb->d_offset, 1);
356 skb_reset_network_header(skb);
358 /* check if datagram_size has ipv6hdr on FRAG1 */
359 fail |= cb->d_size < sizeof(struct ipv6hdr);
360 /* check if we can dereference the dispatch value */
370 int lowpan_frag_rcv(struct sk_buff *skb, u8 frag_type)
372 struct lowpan_frag_queue *fq;
373 struct net *net = dev_net(skb->dev);
374 struct lowpan_802154_cb *cb = lowpan_802154_cb(skb);
375 struct ieee802154_hdr hdr = {};
378 if (ieee802154_hdr_peek_addrs(skb, &hdr) < 0)
381 err = lowpan_get_cb(skb, frag_type, cb);
385 if (frag_type == LOWPAN_DISPATCH_FRAG1) {
386 err = lowpan_invoke_frag_rx_handlers(skb);
387 if (err == NET_RX_DROP)
391 if (cb->d_size > IPV6_MIN_MTU) {
392 net_warn_ratelimited("lowpan_frag_rcv: datagram size exceeds MTU\n");
396 fq = fq_find(net, cb, &hdr.source, &hdr.dest);
400 spin_lock(&fq->q.lock);
401 ret = lowpan_frag_queue(fq, skb, frag_type);
402 spin_unlock(&fq->q.lock);
404 inet_frag_put(&fq->q);
415 static struct ctl_table lowpan_frags_ns_ctl_table[] = {
417 .procname = "6lowpanfrag_high_thresh",
418 .data = &init_net.ieee802154_lowpan.frags.high_thresh,
419 .maxlen = sizeof(unsigned long),
421 .proc_handler = proc_doulongvec_minmax,
422 .extra1 = &init_net.ieee802154_lowpan.frags.low_thresh
425 .procname = "6lowpanfrag_low_thresh",
426 .data = &init_net.ieee802154_lowpan.frags.low_thresh,
427 .maxlen = sizeof(unsigned long),
429 .proc_handler = proc_doulongvec_minmax,
430 .extra2 = &init_net.ieee802154_lowpan.frags.high_thresh
433 .procname = "6lowpanfrag_time",
434 .data = &init_net.ieee802154_lowpan.frags.timeout,
435 .maxlen = sizeof(int),
437 .proc_handler = proc_dointvec_jiffies,
442 /* secret interval has been deprecated */
443 static int lowpan_frags_secret_interval_unused;
444 static struct ctl_table lowpan_frags_ctl_table[] = {
446 .procname = "6lowpanfrag_secret_interval",
447 .data = &lowpan_frags_secret_interval_unused,
448 .maxlen = sizeof(int),
450 .proc_handler = proc_dointvec_jiffies,
455 static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
457 struct ctl_table *table;
458 struct ctl_table_header *hdr;
459 struct netns_ieee802154_lowpan *ieee802154_lowpan =
460 net_ieee802154_lowpan(net);
462 table = lowpan_frags_ns_ctl_table;
463 if (!net_eq(net, &init_net)) {
464 table = kmemdup(table, sizeof(lowpan_frags_ns_ctl_table),
469 table[0].data = &ieee802154_lowpan->frags.high_thresh;
470 table[0].extra1 = &ieee802154_lowpan->frags.low_thresh;
471 table[0].extra2 = &init_net.ieee802154_lowpan.frags.high_thresh;
472 table[1].data = &ieee802154_lowpan->frags.low_thresh;
473 table[1].extra2 = &ieee802154_lowpan->frags.high_thresh;
474 table[2].data = &ieee802154_lowpan->frags.timeout;
476 /* Don't export sysctls to unprivileged users */
477 if (net->user_ns != &init_user_ns)
478 table[0].procname = NULL;
481 hdr = register_net_sysctl(net, "net/ieee802154/6lowpan", table);
485 ieee802154_lowpan->sysctl.frags_hdr = hdr;
489 if (!net_eq(net, &init_net))
495 static void __net_exit lowpan_frags_ns_sysctl_unregister(struct net *net)
497 struct ctl_table *table;
498 struct netns_ieee802154_lowpan *ieee802154_lowpan =
499 net_ieee802154_lowpan(net);
501 table = ieee802154_lowpan->sysctl.frags_hdr->ctl_table_arg;
502 unregister_net_sysctl_table(ieee802154_lowpan->sysctl.frags_hdr);
503 if (!net_eq(net, &init_net))
507 static struct ctl_table_header *lowpan_ctl_header;
509 static int __init lowpan_frags_sysctl_register(void)
511 lowpan_ctl_header = register_net_sysctl(&init_net,
512 "net/ieee802154/6lowpan",
513 lowpan_frags_ctl_table);
514 return lowpan_ctl_header == NULL ? -ENOMEM : 0;
517 static void lowpan_frags_sysctl_unregister(void)
519 unregister_net_sysctl_table(lowpan_ctl_header);
522 static inline int lowpan_frags_ns_sysctl_register(struct net *net)
527 static inline void lowpan_frags_ns_sysctl_unregister(struct net *net)
531 static inline int __init lowpan_frags_sysctl_register(void)
536 static inline void lowpan_frags_sysctl_unregister(void)
541 static int __net_init lowpan_frags_init_net(struct net *net)
543 struct netns_ieee802154_lowpan *ieee802154_lowpan =
544 net_ieee802154_lowpan(net);
547 ieee802154_lowpan->frags.high_thresh = IPV6_FRAG_HIGH_THRESH;
548 ieee802154_lowpan->frags.low_thresh = IPV6_FRAG_LOW_THRESH;
549 ieee802154_lowpan->frags.timeout = IPV6_FRAG_TIMEOUT;
550 ieee802154_lowpan->frags.f = &lowpan_frags;
552 res = inet_frags_init_net(&ieee802154_lowpan->frags);
555 res = lowpan_frags_ns_sysctl_register(net);
557 inet_frags_exit_net(&ieee802154_lowpan->frags);
561 static void __net_exit lowpan_frags_exit_net(struct net *net)
563 struct netns_ieee802154_lowpan *ieee802154_lowpan =
564 net_ieee802154_lowpan(net);
566 lowpan_frags_ns_sysctl_unregister(net);
567 inet_frags_exit_net(&ieee802154_lowpan->frags);
570 static struct pernet_operations lowpan_frags_ops = {
571 .init = lowpan_frags_init_net,
572 .exit = lowpan_frags_exit_net,
575 static u32 lowpan_key_hashfn(const void *data, u32 len, u32 seed)
578 sizeof(struct frag_lowpan_compare_key) / sizeof(u32), seed);
581 static u32 lowpan_obj_hashfn(const void *data, u32 len, u32 seed)
583 const struct inet_frag_queue *fq = data;
585 return jhash2((const u32 *)&fq->key,
586 sizeof(struct frag_lowpan_compare_key) / sizeof(u32), seed);
589 static int lowpan_obj_cmpfn(struct rhashtable_compare_arg *arg, const void *ptr)
591 const struct frag_lowpan_compare_key *key = arg->key;
592 const struct inet_frag_queue *fq = ptr;
594 return !!memcmp(&fq->key, key, sizeof(*key));
597 static const struct rhashtable_params lowpan_rhash_params = {
598 .head_offset = offsetof(struct inet_frag_queue, node),
599 .hashfn = lowpan_key_hashfn,
600 .obj_hashfn = lowpan_obj_hashfn,
601 .obj_cmpfn = lowpan_obj_cmpfn,
602 .automatic_shrinking = true,
605 int __init lowpan_net_frag_init(void)
609 lowpan_frags.constructor = lowpan_frag_init;
610 lowpan_frags.destructor = NULL;
611 lowpan_frags.qsize = sizeof(struct frag_queue);
612 lowpan_frags.frag_expire = lowpan_frag_expire;
613 lowpan_frags.frags_cache_name = lowpan_frags_cache_name;
614 lowpan_frags.rhash_params = lowpan_rhash_params;
615 ret = inet_frags_init(&lowpan_frags);
619 ret = lowpan_frags_sysctl_register();
623 ret = register_pernet_subsys(&lowpan_frags_ops);
629 lowpan_frags_sysctl_unregister();
631 inet_frags_fini(&lowpan_frags);
635 void lowpan_net_frag_exit(void)
637 lowpan_frags_sysctl_unregister();
638 unregister_pernet_subsys(&lowpan_frags_ops);
639 inet_frags_fini(&lowpan_frags);