2 * IPv6 fragment reassembly for connection tracking
4 * Copyright (C)2004 USAGI/WIDE Project
7 * Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
9 * Based on: net/ipv6/reassembly.c
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; either version
14 * 2 of the License, or (at your option) any later version.
17 #include <linux/errno.h>
18 #include <linux/types.h>
19 #include <linux/string.h>
20 #include <linux/socket.h>
21 #include <linux/sockios.h>
22 #include <linux/jiffies.h>
23 #include <linux/net.h>
24 #include <linux/list.h>
25 #include <linux/netdevice.h>
26 #include <linux/in6.h>
27 #include <linux/ipv6.h>
28 #include <linux/icmpv6.h>
29 #include <linux/random.h>
30 #include <linux/jhash.h>
34 #include <net/inet_frag.h>
37 #include <net/protocol.h>
38 #include <net/transp_v6.h>
39 #include <net/rawv6.h>
40 #include <net/ndisc.h>
41 #include <net/addrconf.h>
42 #include <linux/sysctl.h>
43 #include <linux/netfilter.h>
44 #include <linux/netfilter_ipv6.h>
45 #include <linux/kernel.h>
46 #include <linux/module.h>
48 #define NF_CT_FRAG6_HIGH_THRESH 262144 /* == 256*1024 */
49 #define NF_CT_FRAG6_LOW_THRESH 196608 /* == 192*1024 */
50 #define NF_CT_FRAG6_TIMEOUT IPV6_FRAG_TIMEOUT
52 struct nf_ct_frag6_skb_cb
54 struct inet6_skb_parm h
;
59 #define NFCT_FRAG6_CB(skb) ((struct nf_ct_frag6_skb_cb*)((skb)->cb))
61 struct nf_ct_frag6_queue
63 struct inet_frag_queue q
;
65 __be32 id
; /* fragment id */
66 struct in6_addr saddr
;
67 struct in6_addr daddr
;
73 struct inet_frags_ctl nf_frags_ctl __read_mostly
= {
74 .high_thresh
= 256 * 1024,
75 .low_thresh
= 192 * 1024,
76 .timeout
= IPV6_FRAG_TIMEOUT
,
77 .secret_interval
= 10 * 60 * HZ
,
80 static struct inet_frags nf_frags
;
82 static unsigned int ip6qhashfn(__be32 id
, struct in6_addr
*saddr
,
83 struct in6_addr
*daddr
)
87 a
= (__force u32
)saddr
->s6_addr32
[0];
88 b
= (__force u32
)saddr
->s6_addr32
[1];
89 c
= (__force u32
)saddr
->s6_addr32
[2];
91 a
+= JHASH_GOLDEN_RATIO
;
92 b
+= JHASH_GOLDEN_RATIO
;
96 a
+= (__force u32
)saddr
->s6_addr32
[3];
97 b
+= (__force u32
)daddr
->s6_addr32
[0];
98 c
+= (__force u32
)daddr
->s6_addr32
[1];
101 a
+= (__force u32
)daddr
->s6_addr32
[2];
102 b
+= (__force u32
)daddr
->s6_addr32
[3];
103 c
+= (__force u32
)id
;
104 __jhash_mix(a
, b
, c
);
106 return c
& (INETFRAGS_HASHSZ
- 1);
109 static unsigned int nf_hashfn(struct inet_frag_queue
*q
)
111 struct nf_ct_frag6_queue
*nq
;
113 nq
= container_of(q
, struct nf_ct_frag6_queue
, q
);
114 return ip6qhashfn(nq
->id
, &nq
->saddr
, &nq
->daddr
);
117 static void nf_skb_free(struct sk_buff
*skb
)
119 if (NFCT_FRAG6_CB(skb
)->orig
)
120 kfree_skb(NFCT_FRAG6_CB(skb
)->orig
);
123 /* Memory Tracking Functions. */
124 static inline void frag_kfree_skb(struct sk_buff
*skb
, unsigned int *work
)
127 *work
-= skb
->truesize
;
128 atomic_sub(skb
->truesize
, &nf_frags
.mem
);
133 static void nf_frag_free(struct inet_frag_queue
*q
)
135 kfree(container_of(q
, struct nf_ct_frag6_queue
, q
));
138 /* Destruction primitives. */
140 static __inline__
void fq_put(struct nf_ct_frag6_queue
*fq
)
142 inet_frag_put(&fq
->q
, &nf_frags
);
145 /* Kill fq entry. It is not destroyed immediately,
146 * because caller (and someone more) holds reference count.
148 static __inline__
void fq_kill(struct nf_ct_frag6_queue
*fq
)
150 inet_frag_kill(&fq
->q
, &nf_frags
);
153 static void nf_ct_frag6_evictor(void)
155 inet_frag_evictor(&nf_frags
);
158 static void nf_ct_frag6_expire(unsigned long data
)
160 struct nf_ct_frag6_queue
*fq
;
162 fq
= container_of((struct inet_frag_queue
*)data
,
163 struct nf_ct_frag6_queue
, q
);
165 spin_lock(&fq
->q
.lock
);
167 if (fq
->q
.last_in
& COMPLETE
)
173 spin_unlock(&fq
->q
.lock
);
177 /* Creation primitives. */
179 static __inline__
struct nf_ct_frag6_queue
*
180 fq_find(__be32 id
, struct in6_addr
*src
, struct in6_addr
*dst
)
182 struct inet_frag_queue
*q
;
183 struct ip6_create_arg arg
;
189 hash
= ip6qhashfn(id
, src
, dst
);
191 q
= inet_frag_find(&nf_frags
, &arg
, hash
);
195 return container_of(q
, struct nf_ct_frag6_queue
, q
);
198 pr_debug("Can't alloc new queue\n");
203 static int nf_ct_frag6_queue(struct nf_ct_frag6_queue
*fq
, struct sk_buff
*skb
,
204 struct frag_hdr
*fhdr
, int nhoff
)
206 struct sk_buff
*prev
, *next
;
209 if (fq
->q
.last_in
& COMPLETE
) {
210 pr_debug("Allready completed\n");
214 offset
= ntohs(fhdr
->frag_off
) & ~0x7;
215 end
= offset
+ (ntohs(ipv6_hdr(skb
)->payload_len
) -
216 ((u8
*)(fhdr
+ 1) - (u8
*)(ipv6_hdr(skb
) + 1)));
218 if ((unsigned int)end
> IPV6_MAXPLEN
) {
219 pr_debug("offset is too large.\n");
223 if (skb
->ip_summed
== CHECKSUM_COMPLETE
) {
224 const unsigned char *nh
= skb_network_header(skb
);
225 skb
->csum
= csum_sub(skb
->csum
,
226 csum_partial(nh
, (u8
*)(fhdr
+ 1) - nh
,
230 /* Is this the final fragment? */
231 if (!(fhdr
->frag_off
& htons(IP6_MF
))) {
232 /* If we already have some bits beyond end
233 * or have different end, the segment is corrupted.
235 if (end
< fq
->q
.len
||
236 ((fq
->q
.last_in
& LAST_IN
) && end
!= fq
->q
.len
)) {
237 pr_debug("already received last fragment\n");
240 fq
->q
.last_in
|= LAST_IN
;
243 /* Check if the fragment is rounded to 8 bytes.
244 * Required by the RFC.
247 /* RFC2460 says always send parameter problem in
250 pr_debug("end of fragment not rounded to 8 bytes.\n");
253 if (end
> fq
->q
.len
) {
254 /* Some bits beyond end -> corruption. */
255 if (fq
->q
.last_in
& LAST_IN
) {
256 pr_debug("last packet already reached.\n");
266 /* Point into the IP datagram 'data' part. */
267 if (!pskb_pull(skb
, (u8
*) (fhdr
+ 1) - skb
->data
)) {
268 pr_debug("queue: message is too short.\n");
271 if (pskb_trim_rcsum(skb
, end
- offset
)) {
272 pr_debug("Can't trim\n");
276 /* Find out which fragments are in front and at the back of us
277 * in the chain of fragments so far. We must know where to put
278 * this fragment, right?
281 for (next
= fq
->q
.fragments
; next
!= NULL
; next
= next
->next
) {
282 if (NFCT_FRAG6_CB(next
)->offset
>= offset
)
287 /* We found where to put this one. Check for overlap with
288 * preceding fragment, and, if needed, align things so that
289 * any overlaps are eliminated.
292 int i
= (NFCT_FRAG6_CB(prev
)->offset
+ prev
->len
) - offset
;
297 pr_debug("overlap\n");
300 if (!pskb_pull(skb
, i
)) {
301 pr_debug("Can't pull\n");
304 if (skb
->ip_summed
!= CHECKSUM_UNNECESSARY
)
305 skb
->ip_summed
= CHECKSUM_NONE
;
309 /* Look for overlap with succeeding segments.
310 * If we can merge fragments, do it.
312 while (next
&& NFCT_FRAG6_CB(next
)->offset
< end
) {
313 /* overlap is 'i' bytes */
314 int i
= end
- NFCT_FRAG6_CB(next
)->offset
;
317 /* Eat head of the next overlapped fragment
318 * and leave the loop. The next ones cannot overlap.
320 pr_debug("Eat head of the overlapped parts.: %d", i
);
321 if (!pskb_pull(next
, i
))
325 NFCT_FRAG6_CB(next
)->offset
+= i
;
327 if (next
->ip_summed
!= CHECKSUM_UNNECESSARY
)
328 next
->ip_summed
= CHECKSUM_NONE
;
331 struct sk_buff
*free_it
= next
;
333 /* Old fragmnet is completely overridden with
341 fq
->q
.fragments
= next
;
343 fq
->q
.meat
-= free_it
->len
;
344 frag_kfree_skb(free_it
, NULL
);
348 NFCT_FRAG6_CB(skb
)->offset
= offset
;
350 /* Insert this fragment in the chain of fragments. */
355 fq
->q
.fragments
= skb
;
358 fq
->q
.stamp
= skb
->tstamp
;
359 fq
->q
.meat
+= skb
->len
;
360 atomic_add(skb
->truesize
, &nf_frags
.mem
);
362 /* The first fragment.
363 * nhoffset is obtained from the first fragment, of course.
366 fq
->nhoffset
= nhoff
;
367 fq
->q
.last_in
|= FIRST_IN
;
369 write_lock(&nf_frags
.lock
);
370 list_move_tail(&fq
->q
.lru_list
, &nf_frags
.lru_list
);
371 write_unlock(&nf_frags
.lock
);
379 * Check if this packet is complete.
380 * Returns NULL on failure by any reason, and pointer
381 * to current nexthdr field in reassembled frame.
383 * It is called with locked fq, and caller must check that
384 * queue is eligible for reassembly i.e. it is not COMPLETE,
385 * the last and the first frames arrived and all the bits are here.
387 static struct sk_buff
*
388 nf_ct_frag6_reasm(struct nf_ct_frag6_queue
*fq
, struct net_device
*dev
)
390 struct sk_buff
*fp
, *op
, *head
= fq
->q
.fragments
;
395 BUG_TRAP(head
!= NULL
);
396 BUG_TRAP(NFCT_FRAG6_CB(head
)->offset
== 0);
398 /* Unfragmented part is taken from the first segment. */
399 payload_len
= ((head
->data
- skb_network_header(head
)) -
400 sizeof(struct ipv6hdr
) + fq
->q
.len
-
401 sizeof(struct frag_hdr
));
402 if (payload_len
> IPV6_MAXPLEN
) {
403 pr_debug("payload len is too large.\n");
407 /* Head of list must not be cloned. */
408 if (skb_cloned(head
) && pskb_expand_head(head
, 0, 0, GFP_ATOMIC
)) {
409 pr_debug("skb is cloned but can't expand head");
413 /* If the first fragment is fragmented itself, we split
414 * it to two chunks: the first with data and paged part
415 * and the second, holding only fragments. */
416 if (skb_shinfo(head
)->frag_list
) {
417 struct sk_buff
*clone
;
420 if ((clone
= alloc_skb(0, GFP_ATOMIC
)) == NULL
) {
421 pr_debug("Can't alloc skb\n");
424 clone
->next
= head
->next
;
426 skb_shinfo(clone
)->frag_list
= skb_shinfo(head
)->frag_list
;
427 skb_shinfo(head
)->frag_list
= NULL
;
428 for (i
=0; i
<skb_shinfo(head
)->nr_frags
; i
++)
429 plen
+= skb_shinfo(head
)->frags
[i
].size
;
430 clone
->len
= clone
->data_len
= head
->data_len
- plen
;
431 head
->data_len
-= clone
->len
;
432 head
->len
-= clone
->len
;
434 clone
->ip_summed
= head
->ip_summed
;
436 NFCT_FRAG6_CB(clone
)->orig
= NULL
;
437 atomic_add(clone
->truesize
, &nf_frags
.mem
);
440 /* We have to remove fragment header from datagram and to relocate
441 * header in order to calculate ICV correctly. */
442 skb_network_header(head
)[fq
->nhoffset
] = skb_transport_header(head
)[0];
443 memmove(head
->head
+ sizeof(struct frag_hdr
), head
->head
,
444 (head
->data
- head
->head
) - sizeof(struct frag_hdr
));
445 head
->mac_header
+= sizeof(struct frag_hdr
);
446 head
->network_header
+= sizeof(struct frag_hdr
);
448 skb_shinfo(head
)->frag_list
= head
->next
;
449 skb_reset_transport_header(head
);
450 skb_push(head
, head
->data
- skb_network_header(head
));
451 atomic_sub(head
->truesize
, &nf_frags
.mem
);
453 for (fp
=head
->next
; fp
; fp
= fp
->next
) {
454 head
->data_len
+= fp
->len
;
455 head
->len
+= fp
->len
;
456 if (head
->ip_summed
!= fp
->ip_summed
)
457 head
->ip_summed
= CHECKSUM_NONE
;
458 else if (head
->ip_summed
== CHECKSUM_COMPLETE
)
459 head
->csum
= csum_add(head
->csum
, fp
->csum
);
460 head
->truesize
+= fp
->truesize
;
461 atomic_sub(fp
->truesize
, &nf_frags
.mem
);
466 head
->tstamp
= fq
->q
.stamp
;
467 ipv6_hdr(head
)->payload_len
= htons(payload_len
);
469 /* Yes, and fold redundant checksum back. 8) */
470 if (head
->ip_summed
== CHECKSUM_COMPLETE
)
471 head
->csum
= csum_partial(skb_network_header(head
),
472 skb_network_header_len(head
),
475 fq
->q
.fragments
= NULL
;
477 /* all original skbs are linked into the NFCT_FRAG6_CB(head).orig */
478 fp
= skb_shinfo(head
)->frag_list
;
479 if (NFCT_FRAG6_CB(fp
)->orig
== NULL
)
480 /* at above code, head skb is divided into two skbs. */
483 op
= NFCT_FRAG6_CB(head
)->orig
;
484 for (; fp
; fp
= fp
->next
) {
485 struct sk_buff
*orig
= NFCT_FRAG6_CB(fp
)->orig
;
489 NFCT_FRAG6_CB(fp
)->orig
= NULL
;
496 printk(KERN_DEBUG
"nf_ct_frag6_reasm: payload len = %d\n", payload_len
);
500 printk(KERN_DEBUG
"nf_ct_frag6_reasm: no memory for reassembly\n");
506 * find the header just before Fragment Header.
508 * if success return 0 and set ...
509 * (*prevhdrp): the value of "Next Header Field" in the header
510 * just before Fragment Header.
511 * (*prevhoff): the offset of "Next Header Field" in the header
512 * just before Fragment Header.
513 * (*fhoff) : the offset of Fragment Header.
515 * Based on ipv6_skip_hdr() in net/ipv6/exthdr.c
519 find_prev_fhdr(struct sk_buff
*skb
, u8
*prevhdrp
, int *prevhoff
, int *fhoff
)
521 u8 nexthdr
= ipv6_hdr(skb
)->nexthdr
;
522 const int netoff
= skb_network_offset(skb
);
523 u8 prev_nhoff
= netoff
+ offsetof(struct ipv6hdr
, nexthdr
);
524 int start
= netoff
+ sizeof(struct ipv6hdr
);
525 int len
= skb
->len
- start
;
526 u8 prevhdr
= NEXTHDR_IPV6
;
528 while (nexthdr
!= NEXTHDR_FRAGMENT
) {
529 struct ipv6_opt_hdr hdr
;
532 if (!ipv6_ext_hdr(nexthdr
)) {
535 if (len
< (int)sizeof(struct ipv6_opt_hdr
)) {
536 pr_debug("too short\n");
539 if (nexthdr
== NEXTHDR_NONE
) {
540 pr_debug("next header is none\n");
543 if (skb_copy_bits(skb
, start
, &hdr
, sizeof(hdr
)))
545 if (nexthdr
== NEXTHDR_AUTH
)
546 hdrlen
= (hdr
.hdrlen
+2)<<2;
548 hdrlen
= ipv6_optlen(&hdr
);
553 nexthdr
= hdr
.nexthdr
;
562 *prevhoff
= prev_nhoff
;
568 struct sk_buff
*nf_ct_frag6_gather(struct sk_buff
*skb
)
570 struct sk_buff
*clone
;
571 struct net_device
*dev
= skb
->dev
;
572 struct frag_hdr
*fhdr
;
573 struct nf_ct_frag6_queue
*fq
;
577 struct sk_buff
*ret_skb
= NULL
;
579 /* Jumbo payload inhibits frag. header */
580 if (ipv6_hdr(skb
)->payload_len
== 0) {
581 pr_debug("payload len = 0\n");
585 if (find_prev_fhdr(skb
, &prevhdr
, &nhoff
, &fhoff
) < 0)
588 clone
= skb_clone(skb
, GFP_ATOMIC
);
590 pr_debug("Can't clone skb\n");
594 NFCT_FRAG6_CB(clone
)->orig
= skb
;
596 if (!pskb_may_pull(clone
, fhoff
+ sizeof(*fhdr
))) {
597 pr_debug("message is too short.\n");
601 skb_set_transport_header(clone
, fhoff
);
602 hdr
= ipv6_hdr(clone
);
603 fhdr
= (struct frag_hdr
*)skb_transport_header(clone
);
605 if (!(fhdr
->frag_off
& htons(0xFFF9))) {
606 pr_debug("Invalid fragment offset\n");
607 /* It is not a fragmented frame */
611 if (atomic_read(&nf_frags
.mem
) > nf_frags_ctl
.high_thresh
)
612 nf_ct_frag6_evictor();
614 fq
= fq_find(fhdr
->identification
, &hdr
->saddr
, &hdr
->daddr
);
616 pr_debug("Can't find and can't create new queue\n");
620 spin_lock(&fq
->q
.lock
);
622 if (nf_ct_frag6_queue(fq
, clone
, fhdr
, nhoff
) < 0) {
623 spin_unlock(&fq
->q
.lock
);
624 pr_debug("Can't insert skb to queue\n");
629 if (fq
->q
.last_in
== (FIRST_IN
|LAST_IN
) && fq
->q
.meat
== fq
->q
.len
) {
630 ret_skb
= nf_ct_frag6_reasm(fq
, dev
);
632 pr_debug("Can't reassemble fragmented packets\n");
634 spin_unlock(&fq
->q
.lock
);
644 void nf_ct_frag6_output(unsigned int hooknum
, struct sk_buff
*skb
,
645 struct net_device
*in
, struct net_device
*out
,
646 int (*okfn
)(struct sk_buff
*))
648 struct sk_buff
*s
, *s2
;
650 for (s
= NFCT_FRAG6_CB(skb
)->orig
; s
;) {
651 nf_conntrack_put_reasm(s
->nfct_reasm
);
652 nf_conntrack_get_reasm(skb
);
658 NF_HOOK_THRESH(PF_INET6
, hooknum
, s
, in
, out
, okfn
,
659 NF_IP6_PRI_CONNTRACK_DEFRAG
+ 1);
662 nf_conntrack_put_reasm(skb
);
665 int nf_ct_frag6_kfree_frags(struct sk_buff
*skb
)
667 struct sk_buff
*s
, *s2
;
669 for (s
= NFCT_FRAG6_CB(skb
)->orig
; s
; s
= s2
) {
680 int nf_ct_frag6_init(void)
682 nf_frags
.ctl
= &nf_frags_ctl
;
683 nf_frags
.hashfn
= nf_hashfn
;
684 nf_frags
.constructor
= ip6_frag_init
;
685 nf_frags
.destructor
= nf_frag_free
;
686 nf_frags
.skb_free
= nf_skb_free
;
687 nf_frags
.qsize
= sizeof(struct nf_ct_frag6_queue
);
688 nf_frags
.match
= ip6_frag_match
;
689 nf_frags
.equal
= ip6_frag_equal
;
690 nf_frags
.frag_expire
= nf_ct_frag6_expire
;
691 inet_frags_init(&nf_frags
);
696 void nf_ct_frag6_cleanup(void)
698 inet_frags_fini(&nf_frags
);
700 nf_frags_ctl
.low_thresh
= 0;
701 nf_ct_frag6_evictor();