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 <net/netfilter/ipv6/nf_conntrack_ipv6.h>
43 #include <linux/sysctl.h>
44 #include <linux/netfilter.h>
45 #include <linux/netfilter_ipv6.h>
46 #include <linux/kernel.h>
47 #include <linux/module.h>
49 #define NF_CT_FRAG6_HIGH_THRESH 262144 /* == 256*1024 */
50 #define NF_CT_FRAG6_LOW_THRESH 196608 /* == 192*1024 */
51 #define NF_CT_FRAG6_TIMEOUT IPV6_FRAG_TIMEOUT
53 struct nf_ct_frag6_skb_cb
55 struct inet6_skb_parm h;
60 #define NFCT_FRAG6_CB(skb) ((struct nf_ct_frag6_skb_cb*)((skb)->cb))
62 struct nf_ct_frag6_queue
64 struct inet_frag_queue q;
66 __be32 id; /* fragment id */
67 struct in6_addr saddr;
68 struct in6_addr daddr;
74 static struct inet_frags nf_frags;
75 static struct netns_frags nf_init_frags;
78 struct ctl_table nf_ct_ipv6_sysctl_table[] = {
80 .procname = "nf_conntrack_frag6_timeout",
81 .data = &nf_init_frags.timeout,
82 .maxlen = sizeof(unsigned int),
84 .proc_handler = &proc_dointvec_jiffies,
87 .ctl_name = NET_NF_CONNTRACK_FRAG6_LOW_THRESH,
88 .procname = "nf_conntrack_frag6_low_thresh",
89 .data = &nf_init_frags.low_thresh,
90 .maxlen = sizeof(unsigned int),
92 .proc_handler = &proc_dointvec,
95 .ctl_name = NET_NF_CONNTRACK_FRAG6_HIGH_THRESH,
96 .procname = "nf_conntrack_frag6_high_thresh",
97 .data = &nf_init_frags.high_thresh,
98 .maxlen = sizeof(unsigned int),
100 .proc_handler = &proc_dointvec,
106 static unsigned int ip6qhashfn(__be32 id, const struct in6_addr *saddr,
107 const struct in6_addr *daddr)
111 a = (__force u32)saddr->s6_addr32[0];
112 b = (__force u32)saddr->s6_addr32[1];
113 c = (__force u32)saddr->s6_addr32[2];
115 a += JHASH_GOLDEN_RATIO;
116 b += JHASH_GOLDEN_RATIO;
118 __jhash_mix(a, b, c);
120 a += (__force u32)saddr->s6_addr32[3];
121 b += (__force u32)daddr->s6_addr32[0];
122 c += (__force u32)daddr->s6_addr32[1];
123 __jhash_mix(a, b, c);
125 a += (__force u32)daddr->s6_addr32[2];
126 b += (__force u32)daddr->s6_addr32[3];
127 c += (__force u32)id;
128 __jhash_mix(a, b, c);
130 return c & (INETFRAGS_HASHSZ - 1);
133 static unsigned int nf_hashfn(struct inet_frag_queue *q)
135 const struct nf_ct_frag6_queue *nq;
137 nq = container_of(q, struct nf_ct_frag6_queue, q);
138 return ip6qhashfn(nq->id, &nq->saddr, &nq->daddr);
141 static void nf_skb_free(struct sk_buff *skb)
143 if (NFCT_FRAG6_CB(skb)->orig)
144 kfree_skb(NFCT_FRAG6_CB(skb)->orig);
147 /* Memory Tracking Functions. */
148 static inline void frag_kfree_skb(struct sk_buff *skb, unsigned int *work)
151 *work -= skb->truesize;
152 atomic_sub(skb->truesize, &nf_init_frags.mem);
157 /* Destruction primitives. */
159 static __inline__ void fq_put(struct nf_ct_frag6_queue *fq)
161 inet_frag_put(&fq->q, &nf_frags);
164 /* Kill fq entry. It is not destroyed immediately,
165 * because caller (and someone more) holds reference count.
167 static __inline__ void fq_kill(struct nf_ct_frag6_queue *fq)
169 inet_frag_kill(&fq->q, &nf_frags);
172 static void nf_ct_frag6_evictor(void)
175 inet_frag_evictor(&nf_init_frags, &nf_frags);
179 static void nf_ct_frag6_expire(unsigned long data)
181 struct nf_ct_frag6_queue *fq;
183 fq = container_of((struct inet_frag_queue *)data,
184 struct nf_ct_frag6_queue, q);
186 spin_lock(&fq->q.lock);
188 if (fq->q.last_in & INET_FRAG_COMPLETE)
194 spin_unlock(&fq->q.lock);
198 /* Creation primitives. */
200 static __inline__ struct nf_ct_frag6_queue *
201 fq_find(__be32 id, struct in6_addr *src, struct in6_addr *dst)
203 struct inet_frag_queue *q;
204 struct ip6_create_arg arg;
211 read_lock_bh(&nf_frags.lock);
212 hash = ip6qhashfn(id, src, dst);
214 q = inet_frag_find(&nf_init_frags, &nf_frags, &arg, hash);
219 return container_of(q, struct nf_ct_frag6_queue, q);
222 pr_debug("Can't alloc new queue\n");
227 static int nf_ct_frag6_queue(struct nf_ct_frag6_queue *fq, struct sk_buff *skb,
228 const struct frag_hdr *fhdr, int nhoff)
230 struct sk_buff *prev, *next;
233 if (fq->q.last_in & INET_FRAG_COMPLETE) {
234 pr_debug("Allready completed\n");
238 offset = ntohs(fhdr->frag_off) & ~0x7;
239 end = offset + (ntohs(ipv6_hdr(skb)->payload_len) -
240 ((u8 *)(fhdr + 1) - (u8 *)(ipv6_hdr(skb) + 1)));
242 if ((unsigned int)end > IPV6_MAXPLEN) {
243 pr_debug("offset is too large.\n");
247 if (skb->ip_summed == CHECKSUM_COMPLETE) {
248 const unsigned char *nh = skb_network_header(skb);
249 skb->csum = csum_sub(skb->csum,
250 csum_partial(nh, (u8 *)(fhdr + 1) - nh,
254 /* Is this the final fragment? */
255 if (!(fhdr->frag_off & htons(IP6_MF))) {
256 /* If we already have some bits beyond end
257 * or have different end, the segment is corrupted.
259 if (end < fq->q.len ||
260 ((fq->q.last_in & INET_FRAG_LAST_IN) && end != fq->q.len)) {
261 pr_debug("already received last fragment\n");
264 fq->q.last_in |= INET_FRAG_LAST_IN;
267 /* Check if the fragment is rounded to 8 bytes.
268 * Required by the RFC.
271 /* RFC2460 says always send parameter problem in
274 pr_debug("end of fragment not rounded to 8 bytes.\n");
277 if (end > fq->q.len) {
278 /* Some bits beyond end -> corruption. */
279 if (fq->q.last_in & INET_FRAG_LAST_IN) {
280 pr_debug("last packet already reached.\n");
290 /* Point into the IP datagram 'data' part. */
291 if (!pskb_pull(skb, (u8 *) (fhdr + 1) - skb->data)) {
292 pr_debug("queue: message is too short.\n");
295 if (pskb_trim_rcsum(skb, end - offset)) {
296 pr_debug("Can't trim\n");
300 /* Find out which fragments are in front and at the back of us
301 * in the chain of fragments so far. We must know where to put
302 * this fragment, right?
305 for (next = fq->q.fragments; next != NULL; next = next->next) {
306 if (NFCT_FRAG6_CB(next)->offset >= offset)
311 /* We found where to put this one. Check for overlap with
312 * preceding fragment, and, if needed, align things so that
313 * any overlaps are eliminated.
316 int i = (NFCT_FRAG6_CB(prev)->offset + prev->len) - offset;
321 pr_debug("overlap\n");
324 if (!pskb_pull(skb, i)) {
325 pr_debug("Can't pull\n");
328 if (skb->ip_summed != CHECKSUM_UNNECESSARY)
329 skb->ip_summed = CHECKSUM_NONE;
333 /* Look for overlap with succeeding segments.
334 * If we can merge fragments, do it.
336 while (next && NFCT_FRAG6_CB(next)->offset < end) {
337 /* overlap is 'i' bytes */
338 int i = end - NFCT_FRAG6_CB(next)->offset;
341 /* Eat head of the next overlapped fragment
342 * and leave the loop. The next ones cannot overlap.
344 pr_debug("Eat head of the overlapped parts.: %d", i);
345 if (!pskb_pull(next, i))
349 NFCT_FRAG6_CB(next)->offset += i;
351 if (next->ip_summed != CHECKSUM_UNNECESSARY)
352 next->ip_summed = CHECKSUM_NONE;
355 struct sk_buff *free_it = next;
357 /* Old fragmnet is completely overridden with
365 fq->q.fragments = next;
367 fq->q.meat -= free_it->len;
368 frag_kfree_skb(free_it, NULL);
372 NFCT_FRAG6_CB(skb)->offset = offset;
374 /* Insert this fragment in the chain of fragments. */
379 fq->q.fragments = skb;
382 fq->q.stamp = skb->tstamp;
383 fq->q.meat += skb->len;
384 atomic_add(skb->truesize, &nf_init_frags.mem);
386 /* The first fragment.
387 * nhoffset is obtained from the first fragment, of course.
390 fq->nhoffset = nhoff;
391 fq->q.last_in |= INET_FRAG_FIRST_IN;
393 write_lock(&nf_frags.lock);
394 list_move_tail(&fq->q.lru_list, &nf_init_frags.lru_list);
395 write_unlock(&nf_frags.lock);
403 * Check if this packet is complete.
404 * Returns NULL on failure by any reason, and pointer
405 * to current nexthdr field in reassembled frame.
407 * It is called with locked fq, and caller must check that
408 * queue is eligible for reassembly i.e. it is not COMPLETE,
409 * the last and the first frames arrived and all the bits are here.
411 static struct sk_buff *
412 nf_ct_frag6_reasm(struct nf_ct_frag6_queue *fq, struct net_device *dev)
414 struct sk_buff *fp, *op, *head = fq->q.fragments;
419 WARN_ON(head == NULL);
420 WARN_ON(NFCT_FRAG6_CB(head)->offset != 0);
422 /* Unfragmented part is taken from the first segment. */
423 payload_len = ((head->data - skb_network_header(head)) -
424 sizeof(struct ipv6hdr) + fq->q.len -
425 sizeof(struct frag_hdr));
426 if (payload_len > IPV6_MAXPLEN) {
427 pr_debug("payload len is too large.\n");
431 /* Head of list must not be cloned. */
432 if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC)) {
433 pr_debug("skb is cloned but can't expand head");
437 /* If the first fragment is fragmented itself, we split
438 * it to two chunks: the first with data and paged part
439 * and the second, holding only fragments. */
440 if (skb_shinfo(head)->frag_list) {
441 struct sk_buff *clone;
444 if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) {
445 pr_debug("Can't alloc skb\n");
448 clone->next = head->next;
450 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
451 skb_shinfo(head)->frag_list = NULL;
452 for (i=0; i<skb_shinfo(head)->nr_frags; i++)
453 plen += skb_shinfo(head)->frags[i].size;
454 clone->len = clone->data_len = head->data_len - plen;
455 head->data_len -= clone->len;
456 head->len -= clone->len;
458 clone->ip_summed = head->ip_summed;
460 NFCT_FRAG6_CB(clone)->orig = NULL;
461 atomic_add(clone->truesize, &nf_init_frags.mem);
464 /* We have to remove fragment header from datagram and to relocate
465 * header in order to calculate ICV correctly. */
466 skb_network_header(head)[fq->nhoffset] = skb_transport_header(head)[0];
467 memmove(head->head + sizeof(struct frag_hdr), head->head,
468 (head->data - head->head) - sizeof(struct frag_hdr));
469 head->mac_header += sizeof(struct frag_hdr);
470 head->network_header += sizeof(struct frag_hdr);
472 skb_shinfo(head)->frag_list = head->next;
473 skb_reset_transport_header(head);
474 skb_push(head, head->data - skb_network_header(head));
475 atomic_sub(head->truesize, &nf_init_frags.mem);
477 for (fp=head->next; fp; fp = fp->next) {
478 head->data_len += fp->len;
479 head->len += fp->len;
480 if (head->ip_summed != fp->ip_summed)
481 head->ip_summed = CHECKSUM_NONE;
482 else if (head->ip_summed == CHECKSUM_COMPLETE)
483 head->csum = csum_add(head->csum, fp->csum);
484 head->truesize += fp->truesize;
485 atomic_sub(fp->truesize, &nf_init_frags.mem);
490 head->tstamp = fq->q.stamp;
491 ipv6_hdr(head)->payload_len = htons(payload_len);
493 /* Yes, and fold redundant checksum back. 8) */
494 if (head->ip_summed == CHECKSUM_COMPLETE)
495 head->csum = csum_partial(skb_network_header(head),
496 skb_network_header_len(head),
499 fq->q.fragments = NULL;
501 /* all original skbs are linked into the NFCT_FRAG6_CB(head).orig */
502 fp = skb_shinfo(head)->frag_list;
503 if (NFCT_FRAG6_CB(fp)->orig == NULL)
504 /* at above code, head skb is divided into two skbs. */
507 op = NFCT_FRAG6_CB(head)->orig;
508 for (; fp; fp = fp->next) {
509 struct sk_buff *orig = NFCT_FRAG6_CB(fp)->orig;
513 NFCT_FRAG6_CB(fp)->orig = NULL;
520 printk(KERN_DEBUG "nf_ct_frag6_reasm: payload len = %d\n", payload_len);
524 printk(KERN_DEBUG "nf_ct_frag6_reasm: no memory for reassembly\n");
530 * find the header just before Fragment Header.
532 * if success return 0 and set ...
533 * (*prevhdrp): the value of "Next Header Field" in the header
534 * just before Fragment Header.
535 * (*prevhoff): the offset of "Next Header Field" in the header
536 * just before Fragment Header.
537 * (*fhoff) : the offset of Fragment Header.
539 * Based on ipv6_skip_hdr() in net/ipv6/exthdr.c
543 find_prev_fhdr(struct sk_buff *skb, u8 *prevhdrp, int *prevhoff, int *fhoff)
545 u8 nexthdr = ipv6_hdr(skb)->nexthdr;
546 const int netoff = skb_network_offset(skb);
547 u8 prev_nhoff = netoff + offsetof(struct ipv6hdr, nexthdr);
548 int start = netoff + sizeof(struct ipv6hdr);
549 int len = skb->len - start;
550 u8 prevhdr = NEXTHDR_IPV6;
552 while (nexthdr != NEXTHDR_FRAGMENT) {
553 struct ipv6_opt_hdr hdr;
556 if (!ipv6_ext_hdr(nexthdr)) {
559 if (len < (int)sizeof(struct ipv6_opt_hdr)) {
560 pr_debug("too short\n");
563 if (nexthdr == NEXTHDR_NONE) {
564 pr_debug("next header is none\n");
567 if (skb_copy_bits(skb, start, &hdr, sizeof(hdr)))
569 if (nexthdr == NEXTHDR_AUTH)
570 hdrlen = (hdr.hdrlen+2)<<2;
572 hdrlen = ipv6_optlen(&hdr);
577 nexthdr = hdr.nexthdr;
586 *prevhoff = prev_nhoff;
592 struct sk_buff *nf_ct_frag6_gather(struct sk_buff *skb)
594 struct sk_buff *clone;
595 struct net_device *dev = skb->dev;
596 struct frag_hdr *fhdr;
597 struct nf_ct_frag6_queue *fq;
601 struct sk_buff *ret_skb = NULL;
603 /* Jumbo payload inhibits frag. header */
604 if (ipv6_hdr(skb)->payload_len == 0) {
605 pr_debug("payload len = 0\n");
609 if (find_prev_fhdr(skb, &prevhdr, &nhoff, &fhoff) < 0)
612 clone = skb_clone(skb, GFP_ATOMIC);
614 pr_debug("Can't clone skb\n");
618 NFCT_FRAG6_CB(clone)->orig = skb;
620 if (!pskb_may_pull(clone, fhoff + sizeof(*fhdr))) {
621 pr_debug("message is too short.\n");
625 skb_set_transport_header(clone, fhoff);
626 hdr = ipv6_hdr(clone);
627 fhdr = (struct frag_hdr *)skb_transport_header(clone);
629 if (!(fhdr->frag_off & htons(0xFFF9))) {
630 pr_debug("Invalid fragment offset\n");
631 /* It is not a fragmented frame */
635 if (atomic_read(&nf_init_frags.mem) > nf_init_frags.high_thresh)
636 nf_ct_frag6_evictor();
638 fq = fq_find(fhdr->identification, &hdr->saddr, &hdr->daddr);
640 pr_debug("Can't find and can't create new queue\n");
644 spin_lock_bh(&fq->q.lock);
646 if (nf_ct_frag6_queue(fq, clone, fhdr, nhoff) < 0) {
647 spin_unlock_bh(&fq->q.lock);
648 pr_debug("Can't insert skb to queue\n");
653 if (fq->q.last_in == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
654 fq->q.meat == fq->q.len) {
655 ret_skb = nf_ct_frag6_reasm(fq, dev);
657 pr_debug("Can't reassemble fragmented packets\n");
659 spin_unlock_bh(&fq->q.lock);
669 void nf_ct_frag6_output(unsigned int hooknum, struct sk_buff *skb,
670 struct net_device *in, struct net_device *out,
671 int (*okfn)(struct sk_buff *))
673 struct sk_buff *s, *s2;
675 for (s = NFCT_FRAG6_CB(skb)->orig; s;) {
676 nf_conntrack_put_reasm(s->nfct_reasm);
677 nf_conntrack_get_reasm(skb);
683 NF_HOOK_THRESH(PF_INET6, hooknum, s, in, out, okfn,
684 NF_IP6_PRI_CONNTRACK_DEFRAG + 1);
687 nf_conntrack_put_reasm(skb);
690 int nf_ct_frag6_init(void)
692 nf_frags.hashfn = nf_hashfn;
693 nf_frags.constructor = ip6_frag_init;
694 nf_frags.destructor = NULL;
695 nf_frags.skb_free = nf_skb_free;
696 nf_frags.qsize = sizeof(struct nf_ct_frag6_queue);
697 nf_frags.match = ip6_frag_match;
698 nf_frags.frag_expire = nf_ct_frag6_expire;
699 nf_frags.secret_interval = 10 * 60 * HZ;
700 nf_init_frags.timeout = IPV6_FRAG_TIMEOUT;
701 nf_init_frags.high_thresh = 256 * 1024;
702 nf_init_frags.low_thresh = 192 * 1024;
703 inet_frags_init_net(&nf_init_frags);
704 inet_frags_init(&nf_frags);
709 void nf_ct_frag6_cleanup(void)
711 inet_frags_fini(&nf_frags);
713 nf_init_frags.low_thresh = 0;
714 nf_ct_frag6_evictor();