1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * IPv6 fragment reassembly for connection tracking
5 * Copyright (C)2004 USAGI/WIDE Project
8 * Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
10 * Based on: net/ipv6/reassembly.c
13 #define pr_fmt(fmt) "IPv6-nf: " fmt
15 #include <linux/errno.h>
16 #include <linux/types.h>
17 #include <linux/string.h>
18 #include <linux/socket.h>
19 #include <linux/sockios.h>
20 #include <linux/jiffies.h>
21 #include <linux/net.h>
22 #include <linux/list.h>
23 #include <linux/netdevice.h>
24 #include <linux/in6.h>
25 #include <linux/ipv6.h>
26 #include <linux/icmpv6.h>
27 #include <linux/random.h>
28 #include <linux/slab.h>
32 #include <net/ipv6_frag.h>
34 #include <net/protocol.h>
35 #include <net/transp_v6.h>
36 #include <net/rawv6.h>
37 #include <net/ndisc.h>
38 #include <net/addrconf.h>
39 #include <net/inet_ecn.h>
40 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
41 #include <linux/sysctl.h>
42 #include <linux/netfilter.h>
43 #include <linux/netfilter_ipv6.h>
44 #include <linux/kernel.h>
45 #include <linux/module.h>
46 #include <net/netfilter/ipv6/nf_defrag_ipv6.h>
48 static const char nf_frags_cache_name
[] = "nf-frags";
50 static struct inet_frags nf_frags
;
54 static struct ctl_table nf_ct_frag6_sysctl_table
[] = {
56 .procname
= "nf_conntrack_frag6_timeout",
57 .maxlen
= sizeof(unsigned int),
59 .proc_handler
= proc_dointvec_jiffies
,
62 .procname
= "nf_conntrack_frag6_low_thresh",
63 .maxlen
= sizeof(unsigned long),
65 .proc_handler
= proc_doulongvec_minmax
,
68 .procname
= "nf_conntrack_frag6_high_thresh",
69 .maxlen
= sizeof(unsigned long),
71 .proc_handler
= proc_doulongvec_minmax
,
76 static int nf_ct_frag6_sysctl_register(struct net
*net
)
78 struct ctl_table
*table
;
79 struct ctl_table_header
*hdr
;
81 table
= nf_ct_frag6_sysctl_table
;
82 if (!net_eq(net
, &init_net
)) {
83 table
= kmemdup(table
, sizeof(nf_ct_frag6_sysctl_table
),
89 table
[0].data
= &net
->nf_frag
.fqdir
->timeout
;
90 table
[1].data
= &net
->nf_frag
.fqdir
->low_thresh
;
91 table
[1].extra2
= &net
->nf_frag
.fqdir
->high_thresh
;
92 table
[2].data
= &net
->nf_frag
.fqdir
->high_thresh
;
93 table
[2].extra1
= &net
->nf_frag
.fqdir
->low_thresh
;
94 table
[2].extra2
= &init_net
.nf_frag
.fqdir
->high_thresh
;
96 hdr
= register_net_sysctl(net
, "net/netfilter", table
);
100 net
->nf_frag_frags_hdr
= hdr
;
104 if (!net_eq(net
, &init_net
))
110 static void __net_exit
nf_ct_frags6_sysctl_unregister(struct net
*net
)
112 struct ctl_table
*table
;
114 table
= net
->nf_frag_frags_hdr
->ctl_table_arg
;
115 unregister_net_sysctl_table(net
->nf_frag_frags_hdr
);
116 if (!net_eq(net
, &init_net
))
121 static int nf_ct_frag6_sysctl_register(struct net
*net
)
125 static void __net_exit
nf_ct_frags6_sysctl_unregister(struct net
*net
)
130 static int nf_ct_frag6_reasm(struct frag_queue
*fq
, struct sk_buff
*skb
,
131 struct sk_buff
*prev_tail
, struct net_device
*dev
);
133 static inline u8
ip6_frag_ecn(const struct ipv6hdr
*ipv6h
)
135 return 1 << (ipv6_get_dsfield(ipv6h
) & INET_ECN_MASK
);
138 static void nf_ct_frag6_expire(struct timer_list
*t
)
140 struct inet_frag_queue
*frag
= from_timer(frag
, t
, timer
);
141 struct frag_queue
*fq
;
143 fq
= container_of(frag
, struct frag_queue
, q
);
145 ip6frag_expire_frag_queue(fq
->q
.fqdir
->net
, fq
);
148 /* Creation primitives. */
149 static struct frag_queue
*fq_find(struct net
*net
, __be32 id
, u32 user
,
150 const struct ipv6hdr
*hdr
, int iif
)
152 struct frag_v6_compare_key key
= {
159 struct inet_frag_queue
*q
;
161 q
= inet_frag_find(net
->nf_frag
.fqdir
, &key
);
165 return container_of(q
, struct frag_queue
, q
);
169 static int nf_ct_frag6_queue(struct frag_queue
*fq
, struct sk_buff
*skb
,
170 const struct frag_hdr
*fhdr
, int nhoff
)
172 unsigned int payload_len
;
173 struct net_device
*dev
;
174 struct sk_buff
*prev
;
175 int offset
, end
, err
;
178 if (fq
->q
.flags
& INET_FRAG_COMPLETE
) {
179 pr_debug("Already completed\n");
183 payload_len
= ntohs(ipv6_hdr(skb
)->payload_len
);
185 offset
= ntohs(fhdr
->frag_off
) & ~0x7;
186 end
= offset
+ (payload_len
-
187 ((u8
*)(fhdr
+ 1) - (u8
*)(ipv6_hdr(skb
) + 1)));
189 if ((unsigned int)end
> IPV6_MAXPLEN
) {
190 pr_debug("offset is too large.\n");
194 ecn
= ip6_frag_ecn(ipv6_hdr(skb
));
196 if (skb
->ip_summed
== CHECKSUM_COMPLETE
) {
197 const unsigned char *nh
= skb_network_header(skb
);
198 skb
->csum
= csum_sub(skb
->csum
,
199 csum_partial(nh
, (u8
*)(fhdr
+ 1) - nh
,
203 /* Is this the final fragment? */
204 if (!(fhdr
->frag_off
& htons(IP6_MF
))) {
205 /* If we already have some bits beyond end
206 * or have different end, the segment is corrupted.
208 if (end
< fq
->q
.len
||
209 ((fq
->q
.flags
& INET_FRAG_LAST_IN
) && end
!= fq
->q
.len
)) {
210 pr_debug("already received last fragment\n");
213 fq
->q
.flags
|= INET_FRAG_LAST_IN
;
216 /* Check if the fragment is rounded to 8 bytes.
217 * Required by the RFC.
220 /* RFC2460 says always send parameter problem in
223 pr_debug("end of fragment not rounded to 8 bytes.\n");
224 inet_frag_kill(&fq
->q
);
227 if (end
> fq
->q
.len
) {
228 /* Some bits beyond end -> corruption. */
229 if (fq
->q
.flags
& INET_FRAG_LAST_IN
) {
230 pr_debug("last packet already reached.\n");
240 /* Point into the IP datagram 'data' part. */
241 if (!pskb_pull(skb
, (u8
*) (fhdr
+ 1) - skb
->data
)) {
242 pr_debug("queue: message is too short.\n");
245 if (pskb_trim_rcsum(skb
, end
- offset
)) {
246 pr_debug("Can't trim\n");
250 /* Note : skb->rbnode and skb->dev share the same location. */
252 /* Makes sure compiler wont do silly aliasing games */
255 prev
= fq
->q
.fragments_tail
;
256 err
= inet_frag_queue_insert(&fq
->q
, skb
, offset
, end
);
258 if (err
== IPFRAG_DUP
) {
259 /* No error for duplicates, pretend they got queued. */
267 fq
->iif
= dev
->ifindex
;
269 fq
->q
.stamp
= skb
->tstamp
;
270 fq
->q
.meat
+= skb
->len
;
272 if (payload_len
> fq
->q
.max_size
)
273 fq
->q
.max_size
= payload_len
;
274 add_frag_mem_limit(fq
->q
.fqdir
, skb
->truesize
);
276 /* The first fragment.
277 * nhoffset is obtained from the first fragment, of course.
280 fq
->nhoffset
= nhoff
;
281 fq
->q
.flags
|= INET_FRAG_FIRST_IN
;
284 if (fq
->q
.flags
== (INET_FRAG_FIRST_IN
| INET_FRAG_LAST_IN
) &&
285 fq
->q
.meat
== fq
->q
.len
) {
286 unsigned long orefdst
= skb
->_skb_refdst
;
288 skb
->_skb_refdst
= 0UL;
289 err
= nf_ct_frag6_reasm(fq
, skb
, prev
, dev
);
290 skb
->_skb_refdst
= orefdst
;
292 /* After queue has assumed skb ownership, only 0 or
293 * -EINPROGRESS must be returned.
295 return err
? -EINPROGRESS
: 0;
302 inet_frag_kill(&fq
->q
);
309 * Check if this packet is complete.
311 * It is called with locked fq, and caller must check that
312 * queue is eligible for reassembly i.e. it is not COMPLETE,
313 * the last and the first frames arrived and all the bits are here.
315 static int nf_ct_frag6_reasm(struct frag_queue
*fq
, struct sk_buff
*skb
,
316 struct sk_buff
*prev_tail
, struct net_device
*dev
)
322 inet_frag_kill(&fq
->q
);
324 ecn
= ip_frag_ecn_table
[fq
->ecn
];
325 if (unlikely(ecn
== 0xff))
328 reasm_data
= inet_frag_reasm_prepare(&fq
->q
, skb
, prev_tail
);
332 payload_len
= ((skb
->data
- skb_network_header(skb
)) -
333 sizeof(struct ipv6hdr
) + fq
->q
.len
-
334 sizeof(struct frag_hdr
));
335 if (payload_len
> IPV6_MAXPLEN
) {
336 net_dbg_ratelimited("nf_ct_frag6_reasm: payload len = %d\n",
341 /* We have to remove fragment header from datagram and to relocate
342 * header in order to calculate ICV correctly. */
343 skb_network_header(skb
)[fq
->nhoffset
] = skb_transport_header(skb
)[0];
344 memmove(skb
->head
+ sizeof(struct frag_hdr
), skb
->head
,
345 (skb
->data
- skb
->head
) - sizeof(struct frag_hdr
));
346 skb
->mac_header
+= sizeof(struct frag_hdr
);
347 skb
->network_header
+= sizeof(struct frag_hdr
);
349 skb_reset_transport_header(skb
);
351 inet_frag_reasm_finish(&fq
->q
, skb
, reasm_data
);
355 ipv6_hdr(skb
)->payload_len
= htons(payload_len
);
356 ipv6_change_dsfield(ipv6_hdr(skb
), 0xff, ecn
);
357 IP6CB(skb
)->frag_max_size
= sizeof(struct ipv6hdr
) + fq
->q
.max_size
;
359 /* Yes, and fold redundant checksum back. 8) */
360 if (skb
->ip_summed
== CHECKSUM_COMPLETE
)
361 skb
->csum
= csum_partial(skb_network_header(skb
),
362 skb_network_header_len(skb
),
365 fq
->q
.rb_fragments
= RB_ROOT
;
366 fq
->q
.fragments_tail
= NULL
;
367 fq
->q
.last_run_head
= NULL
;
372 inet_frag_kill(&fq
->q
);
377 * find the header just before Fragment Header.
379 * if success return 0 and set ...
380 * (*prevhdrp): the value of "Next Header Field" in the header
381 * just before Fragment Header.
382 * (*prevhoff): the offset of "Next Header Field" in the header
383 * just before Fragment Header.
384 * (*fhoff) : the offset of Fragment Header.
386 * Based on ipv6_skip_hdr() in net/ipv6/exthdr.c
390 find_prev_fhdr(struct sk_buff
*skb
, u8
*prevhdrp
, int *prevhoff
, int *fhoff
)
392 u8 nexthdr
= ipv6_hdr(skb
)->nexthdr
;
393 const int netoff
= skb_network_offset(skb
);
394 u8 prev_nhoff
= netoff
+ offsetof(struct ipv6hdr
, nexthdr
);
395 int start
= netoff
+ sizeof(struct ipv6hdr
);
396 int len
= skb
->len
- start
;
397 u8 prevhdr
= NEXTHDR_IPV6
;
399 while (nexthdr
!= NEXTHDR_FRAGMENT
) {
400 struct ipv6_opt_hdr hdr
;
403 if (!ipv6_ext_hdr(nexthdr
)) {
406 if (nexthdr
== NEXTHDR_NONE
) {
407 pr_debug("next header is none\n");
410 if (len
< (int)sizeof(struct ipv6_opt_hdr
)) {
411 pr_debug("too short\n");
414 if (skb_copy_bits(skb
, start
, &hdr
, sizeof(hdr
)))
416 if (nexthdr
== NEXTHDR_AUTH
)
417 hdrlen
= ipv6_authlen(&hdr
);
419 hdrlen
= ipv6_optlen(&hdr
);
424 nexthdr
= hdr
.nexthdr
;
433 *prevhoff
= prev_nhoff
;
439 int nf_ct_frag6_gather(struct net
*net
, struct sk_buff
*skb
, u32 user
)
441 u16 savethdr
= skb
->transport_header
;
442 int fhoff
, nhoff
, ret
;
443 struct frag_hdr
*fhdr
;
444 struct frag_queue
*fq
;
448 /* Jumbo payload inhibits frag. header */
449 if (ipv6_hdr(skb
)->payload_len
== 0) {
450 pr_debug("payload len = 0\n");
454 if (find_prev_fhdr(skb
, &prevhdr
, &nhoff
, &fhoff
) < 0)
457 if (!pskb_may_pull(skb
, fhoff
+ sizeof(*fhdr
)))
460 skb_set_transport_header(skb
, fhoff
);
462 fhdr
= (struct frag_hdr
*)skb_transport_header(skb
);
465 fq
= fq_find(net
, fhdr
->identification
, user
, hdr
,
466 skb
->dev
? skb
->dev
->ifindex
: 0);
468 pr_debug("Can't find and can't create new queue\n");
472 spin_lock_bh(&fq
->q
.lock
);
474 ret
= nf_ct_frag6_queue(fq
, skb
, fhdr
, nhoff
);
475 if (ret
== -EPROTO
) {
476 skb
->transport_header
= savethdr
;
480 spin_unlock_bh(&fq
->q
.lock
);
481 inet_frag_put(&fq
->q
);
484 EXPORT_SYMBOL_GPL(nf_ct_frag6_gather
);
486 static int nf_ct_net_init(struct net
*net
)
490 res
= fqdir_init(&net
->nf_frag
.fqdir
, &nf_frags
, net
);
494 net
->nf_frag
.fqdir
->high_thresh
= IPV6_FRAG_HIGH_THRESH
;
495 net
->nf_frag
.fqdir
->low_thresh
= IPV6_FRAG_LOW_THRESH
;
496 net
->nf_frag
.fqdir
->timeout
= IPV6_FRAG_TIMEOUT
;
498 res
= nf_ct_frag6_sysctl_register(net
);
500 fqdir_exit(net
->nf_frag
.fqdir
);
504 static void nf_ct_net_pre_exit(struct net
*net
)
506 fqdir_pre_exit(net
->nf_frag
.fqdir
);
509 static void nf_ct_net_exit(struct net
*net
)
511 nf_ct_frags6_sysctl_unregister(net
);
512 fqdir_exit(net
->nf_frag
.fqdir
);
515 static struct pernet_operations nf_ct_net_ops
= {
516 .init
= nf_ct_net_init
,
517 .pre_exit
= nf_ct_net_pre_exit
,
518 .exit
= nf_ct_net_exit
,
521 static const struct rhashtable_params nfct_rhash_params
= {
522 .head_offset
= offsetof(struct inet_frag_queue
, node
),
523 .hashfn
= ip6frag_key_hashfn
,
524 .obj_hashfn
= ip6frag_obj_hashfn
,
525 .obj_cmpfn
= ip6frag_obj_cmpfn
,
526 .automatic_shrinking
= true,
529 int nf_ct_frag6_init(void)
533 nf_frags
.constructor
= ip6frag_init
;
534 nf_frags
.destructor
= NULL
;
535 nf_frags
.qsize
= sizeof(struct frag_queue
);
536 nf_frags
.frag_expire
= nf_ct_frag6_expire
;
537 nf_frags
.frags_cache_name
= nf_frags_cache_name
;
538 nf_frags
.rhash_params
= nfct_rhash_params
;
539 ret
= inet_frags_init(&nf_frags
);
542 ret
= register_pernet_subsys(&nf_ct_net_ops
);
544 inet_frags_fini(&nf_frags
);
550 void nf_ct_frag6_cleanup(void)
552 unregister_pernet_subsys(&nf_ct_net_ops
);
553 inet_frags_fini(&nf_frags
);