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 struct lowpan_frag_info
{
39 struct lowpan_frag_info
*lowpan_cb(struct sk_buff
*skb
)
41 return (struct lowpan_frag_info
*)skb
->cb
;
44 static struct inet_frags lowpan_frags
;
46 static int lowpan_frag_reasm(struct lowpan_frag_queue
*fq
,
47 struct sk_buff
*prev
, struct net_device
*dev
);
49 static unsigned int lowpan_hash_frag(__be16 tag
, u16 d_size
,
50 const struct ieee802154_addr
*saddr
,
51 const struct ieee802154_addr
*daddr
)
55 net_get_random_once(&lowpan_frags
.rnd
, sizeof(lowpan_frags
.rnd
));
56 c
= jhash_3words(ieee802154_addr_hash(saddr
),
57 ieee802154_addr_hash(daddr
),
58 (__force u32
)(tag
+ (d_size
<< 16)),
61 return c
& (INETFRAGS_HASHSZ
- 1);
64 static unsigned int lowpan_hashfn(struct inet_frag_queue
*q
)
66 struct lowpan_frag_queue
*fq
;
68 fq
= container_of(q
, struct lowpan_frag_queue
, q
);
69 return lowpan_hash_frag(fq
->tag
, fq
->d_size
, &fq
->saddr
, &fq
->daddr
);
72 static bool lowpan_frag_match(struct inet_frag_queue
*q
, void *a
)
74 struct lowpan_frag_queue
*fq
;
75 struct lowpan_create_arg
*arg
= a
;
77 fq
= container_of(q
, struct lowpan_frag_queue
, q
);
78 return fq
->tag
== arg
->tag
&& fq
->d_size
== arg
->d_size
&&
79 ieee802154_addr_equal(&fq
->saddr
, arg
->src
) &&
80 ieee802154_addr_equal(&fq
->daddr
, arg
->dst
);
83 static void lowpan_frag_init(struct inet_frag_queue
*q
, void *a
)
85 struct lowpan_frag_queue
*fq
;
86 struct lowpan_create_arg
*arg
= a
;
88 fq
= container_of(q
, struct lowpan_frag_queue
, q
);
91 fq
->d_size
= arg
->d_size
;
92 fq
->saddr
= *arg
->src
;
93 fq
->daddr
= *arg
->dst
;
96 static void lowpan_frag_expire(unsigned long data
)
98 struct frag_queue
*fq
;
101 fq
= container_of((struct inet_frag_queue
*)data
, struct frag_queue
, q
);
102 net
= container_of(fq
->q
.net
, struct net
, ieee802154_lowpan
.frags
);
104 spin_lock(&fq
->q
.lock
);
106 if (fq
->q
.last_in
& INET_FRAG_COMPLETE
)
109 inet_frag_kill(&fq
->q
, &lowpan_frags
);
111 spin_unlock(&fq
->q
.lock
);
112 inet_frag_put(&fq
->q
, &lowpan_frags
);
115 static inline struct lowpan_frag_queue
*
116 fq_find(struct net
*net
, const struct lowpan_frag_info
*frag_info
,
117 const struct ieee802154_addr
*src
,
118 const struct ieee802154_addr
*dst
)
120 struct inet_frag_queue
*q
;
121 struct lowpan_create_arg arg
;
124 arg
.tag
= frag_info
->d_tag
;
125 arg
.d_size
= frag_info
->d_size
;
129 read_lock(&lowpan_frags
.lock
);
130 hash
= lowpan_hash_frag(frag_info
->d_tag
, frag_info
->d_size
, src
, dst
);
132 q
= inet_frag_find(&net
->ieee802154_lowpan
.frags
,
133 &lowpan_frags
, &arg
, hash
);
134 if (IS_ERR_OR_NULL(q
)) {
135 inet_frag_maybe_warn_overflow(q
, pr_fmt());
138 return container_of(q
, struct lowpan_frag_queue
, q
);
141 static int lowpan_frag_queue(struct lowpan_frag_queue
*fq
,
142 struct sk_buff
*skb
, const u8 frag_type
)
144 struct sk_buff
*prev
, *next
;
145 struct net_device
*dev
;
148 if (fq
->q
.last_in
& INET_FRAG_COMPLETE
)
151 offset
= lowpan_cb(skb
)->d_offset
<< 3;
152 end
= lowpan_cb(skb
)->d_size
;
154 /* Is this the final fragment? */
155 if (offset
+ skb
->len
== end
) {
156 /* If we already have some bits beyond end
157 * or have different end, the segment is corrupted.
159 if (end
< fq
->q
.len
||
160 ((fq
->q
.last_in
& INET_FRAG_LAST_IN
) && end
!= fq
->q
.len
))
162 fq
->q
.last_in
|= INET_FRAG_LAST_IN
;
165 if (end
> fq
->q
.len
) {
166 /* Some bits beyond end -> corruption. */
167 if (fq
->q
.last_in
& INET_FRAG_LAST_IN
)
173 /* Find out which fragments are in front and at the back of us
174 * in the chain of fragments so far. We must know where to put
175 * this fragment, right?
177 prev
= fq
->q
.fragments_tail
;
178 if (!prev
|| lowpan_cb(prev
)->d_offset
< lowpan_cb(skb
)->d_offset
) {
183 for (next
= fq
->q
.fragments
; next
!= NULL
; next
= next
->next
) {
184 if (lowpan_cb(next
)->d_offset
>= lowpan_cb(skb
)->d_offset
)
190 /* Insert this fragment in the chain of fragments. */
193 fq
->q
.fragments_tail
= skb
;
197 fq
->q
.fragments
= skb
;
203 fq
->q
.stamp
= skb
->tstamp
;
204 if (frag_type
== LOWPAN_DISPATCH_FRAG1
) {
205 /* Calculate uncomp. 6lowpan header to estimate full size */
206 fq
->q
.meat
+= lowpan_uncompress_size(skb
, NULL
);
207 fq
->q
.last_in
|= INET_FRAG_FIRST_IN
;
209 fq
->q
.meat
+= skb
->len
;
211 add_frag_mem_limit(&fq
->q
, skb
->truesize
);
213 if (fq
->q
.last_in
== (INET_FRAG_FIRST_IN
| INET_FRAG_LAST_IN
) &&
214 fq
->q
.meat
== fq
->q
.len
) {
216 unsigned long orefdst
= skb
->_skb_refdst
;
218 skb
->_skb_refdst
= 0UL;
219 res
= lowpan_frag_reasm(fq
, prev
, dev
);
220 skb
->_skb_refdst
= orefdst
;
224 inet_frag_lru_move(&fq
->q
);
231 /* Check if this packet is complete.
232 * Returns NULL on failure by any reason, and pointer
233 * to current nexthdr field in reassembled frame.
235 * It is called with locked fq, and caller must check that
236 * queue is eligible for reassembly i.e. it is not COMPLETE,
237 * the last and the first frames arrived and all the bits are here.
239 static int lowpan_frag_reasm(struct lowpan_frag_queue
*fq
, struct sk_buff
*prev
,
240 struct net_device
*dev
)
242 struct sk_buff
*fp
, *head
= fq
->q
.fragments
;
245 inet_frag_kill(&fq
->q
, &lowpan_frags
);
247 /* Make the one we just received the head. */
250 fp
= skb_clone(head
, GFP_ATOMIC
);
255 fp
->next
= head
->next
;
257 fq
->q
.fragments_tail
= fp
;
260 skb_morph(head
, fq
->q
.fragments
);
261 head
->next
= fq
->q
.fragments
->next
;
263 consume_skb(fq
->q
.fragments
);
264 fq
->q
.fragments
= head
;
267 /* Head of list must not be cloned. */
268 if (skb_unclone(head
, GFP_ATOMIC
))
271 /* If the first fragment is fragmented itself, we split
272 * it to two chunks: the first with data and paged part
273 * and the second, holding only fragments.
275 if (skb_has_frag_list(head
)) {
276 struct sk_buff
*clone
;
279 clone
= alloc_skb(0, GFP_ATOMIC
);
282 clone
->next
= head
->next
;
284 skb_shinfo(clone
)->frag_list
= skb_shinfo(head
)->frag_list
;
285 skb_frag_list_init(head
);
286 for (i
= 0; i
< skb_shinfo(head
)->nr_frags
; i
++)
287 plen
+= skb_frag_size(&skb_shinfo(head
)->frags
[i
]);
288 clone
->len
= head
->data_len
- plen
;
289 clone
->data_len
= clone
->len
;
290 head
->data_len
-= clone
->len
;
291 head
->len
-= clone
->len
;
292 add_frag_mem_limit(&fq
->q
, clone
->truesize
);
295 WARN_ON(head
== NULL
);
297 sum_truesize
= head
->truesize
;
298 for (fp
= head
->next
; fp
;) {
301 struct sk_buff
*next
= fp
->next
;
303 sum_truesize
+= fp
->truesize
;
304 if (skb_try_coalesce(head
, fp
, &headstolen
, &delta
)) {
305 kfree_skb_partial(fp
, headstolen
);
307 if (!skb_shinfo(head
)->frag_list
)
308 skb_shinfo(head
)->frag_list
= fp
;
309 head
->data_len
+= fp
->len
;
310 head
->len
+= fp
->len
;
311 head
->truesize
+= fp
->truesize
;
315 sub_frag_mem_limit(&fq
->q
, sum_truesize
);
319 head
->tstamp
= fq
->q
.stamp
;
321 fq
->q
.fragments
= NULL
;
322 fq
->q
.fragments_tail
= NULL
;
326 net_dbg_ratelimited("lowpan_frag_reasm: no memory for reassembly\n");
330 static int lowpan_get_frag_info(struct sk_buff
*skb
, const u8 frag_type
,
331 struct lowpan_frag_info
*frag_info
)
334 u8 pattern
= 0, low
= 0;
336 fail
= lowpan_fetch_skb(skb
, &pattern
, 1);
337 fail
|= lowpan_fetch_skb(skb
, &low
, 1);
338 frag_info
->d_size
= (pattern
& 7) << 8 | low
;
339 fail
|= lowpan_fetch_skb(skb
, &frag_info
->d_tag
, 2);
341 if (frag_type
== LOWPAN_DISPATCH_FRAGN
) {
342 fail
|= lowpan_fetch_skb(skb
, &frag_info
->d_offset
, 1);
344 skb_reset_network_header(skb
);
345 frag_info
->d_offset
= 0;
354 int lowpan_frag_rcv(struct sk_buff
*skb
, const u8 frag_type
)
356 struct lowpan_frag_queue
*fq
;
357 struct net
*net
= dev_net(skb
->dev
);
358 struct lowpan_frag_info
*frag_info
= lowpan_cb(skb
);
359 struct ieee802154_addr source
, dest
;
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
> net
->ieee802154_lowpan
.max_dsize
)
372 inet_frag_evictor(&net
->ieee802154_lowpan
.frags
, &lowpan_frags
, false);
374 fq
= fq_find(net
, frag_info
, &source
, &dest
);
377 spin_lock(&fq
->q
.lock
);
378 ret
= lowpan_frag_queue(fq
, skb
, frag_type
);
379 spin_unlock(&fq
->q
.lock
);
381 inet_frag_put(&fq
->q
, &lowpan_frags
);
389 EXPORT_SYMBOL(lowpan_frag_rcv
);
392 static struct ctl_table lowpan_frags_ns_ctl_table
[] = {
394 .procname
= "6lowpanfrag_high_thresh",
395 .data
= &init_net
.ieee802154_lowpan
.frags
.high_thresh
,
396 .maxlen
= sizeof(int),
398 .proc_handler
= proc_dointvec
401 .procname
= "6lowpanfrag_low_thresh",
402 .data
= &init_net
.ieee802154_lowpan
.frags
.low_thresh
,
403 .maxlen
= sizeof(int),
405 .proc_handler
= proc_dointvec
408 .procname
= "6lowpanfrag_time",
409 .data
= &init_net
.ieee802154_lowpan
.frags
.timeout
,
410 .maxlen
= sizeof(int),
412 .proc_handler
= proc_dointvec_jiffies
,
415 .procname
= "6lowpanfrag_max_datagram_size",
416 .data
= &init_net
.ieee802154_lowpan
.max_dsize
,
417 .maxlen
= sizeof(int),
419 .proc_handler
= proc_dointvec
424 static struct ctl_table lowpan_frags_ctl_table
[] = {
426 .procname
= "6lowpanfrag_secret_interval",
427 .data
= &lowpan_frags
.secret_interval
,
428 .maxlen
= sizeof(int),
430 .proc_handler
= proc_dointvec_jiffies
,
435 static int __net_init
lowpan_frags_ns_sysctl_register(struct net
*net
)
437 struct ctl_table
*table
;
438 struct ctl_table_header
*hdr
;
440 table
= lowpan_frags_ns_ctl_table
;
441 if (!net_eq(net
, &init_net
)) {
442 table
= kmemdup(table
, sizeof(lowpan_frags_ns_ctl_table
),
447 table
[0].data
= &net
->ieee802154_lowpan
.frags
.high_thresh
;
448 table
[1].data
= &net
->ieee802154_lowpan
.frags
.low_thresh
;
449 table
[2].data
= &net
->ieee802154_lowpan
.frags
.timeout
;
450 table
[3].data
= &net
->ieee802154_lowpan
.max_dsize
;
452 /* Don't export sysctls to unprivileged users */
453 if (net
->user_ns
!= &init_user_ns
)
454 table
[0].procname
= NULL
;
457 hdr
= register_net_sysctl(net
, "net/ieee802154/6lowpan", table
);
461 net
->ieee802154_lowpan
.sysctl
.frags_hdr
= hdr
;
465 if (!net_eq(net
, &init_net
))
471 static void __net_exit
lowpan_frags_ns_sysctl_unregister(struct net
*net
)
473 struct ctl_table
*table
;
475 table
= net
->ieee802154_lowpan
.sysctl
.frags_hdr
->ctl_table_arg
;
476 unregister_net_sysctl_table(net
->ieee802154_lowpan
.sysctl
.frags_hdr
);
477 if (!net_eq(net
, &init_net
))
481 static struct ctl_table_header
*lowpan_ctl_header
;
483 static int lowpan_frags_sysctl_register(void)
485 lowpan_ctl_header
= register_net_sysctl(&init_net
,
486 "net/ieee802154/6lowpan",
487 lowpan_frags_ctl_table
);
488 return lowpan_ctl_header
== NULL
? -ENOMEM
: 0;
491 static void lowpan_frags_sysctl_unregister(void)
493 unregister_net_sysctl_table(lowpan_ctl_header
);
496 static inline int lowpan_frags_ns_sysctl_register(struct net
*net
)
501 static inline void lowpan_frags_ns_sysctl_unregister(struct net
*net
)
505 static inline int lowpan_frags_sysctl_register(void)
510 static inline void lowpan_frags_sysctl_unregister(void)
515 static int __net_init
lowpan_frags_init_net(struct net
*net
)
517 net
->ieee802154_lowpan
.frags
.high_thresh
= IPV6_FRAG_HIGH_THRESH
;
518 net
->ieee802154_lowpan
.frags
.low_thresh
= IPV6_FRAG_LOW_THRESH
;
519 net
->ieee802154_lowpan
.frags
.timeout
= IPV6_FRAG_TIMEOUT
;
520 net
->ieee802154_lowpan
.max_dsize
= 0xFFFF;
522 inet_frags_init_net(&net
->ieee802154_lowpan
.frags
);
524 return lowpan_frags_ns_sysctl_register(net
);
527 static void __net_exit
lowpan_frags_exit_net(struct net
*net
)
529 lowpan_frags_ns_sysctl_unregister(net
);
530 inet_frags_exit_net(&net
->ieee802154_lowpan
.frags
, &lowpan_frags
);
533 static struct pernet_operations lowpan_frags_ops
= {
534 .init
= lowpan_frags_init_net
,
535 .exit
= lowpan_frags_exit_net
,
538 int __init
lowpan_net_frag_init(void)
542 ret
= lowpan_frags_sysctl_register();
546 ret
= register_pernet_subsys(&lowpan_frags_ops
);
550 lowpan_frags
.hashfn
= lowpan_hashfn
;
551 lowpan_frags
.constructor
= lowpan_frag_init
;
552 lowpan_frags
.destructor
= NULL
;
553 lowpan_frags
.skb_free
= NULL
;
554 lowpan_frags
.qsize
= sizeof(struct frag_queue
);
555 lowpan_frags
.match
= lowpan_frag_match
;
556 lowpan_frags
.frag_expire
= lowpan_frag_expire
;
557 lowpan_frags
.secret_interval
= 10 * 60 * HZ
;
558 inet_frags_init(&lowpan_frags
);
562 lowpan_frags_sysctl_unregister();
566 void lowpan_net_frag_exit(void)
568 inet_frags_fini(&lowpan_frags
);
569 lowpan_frags_sysctl_unregister();
570 unregister_pernet_subsys(&lowpan_frags_ops
);