1// SPDX-License-Identifier: GPL-2.0
2/*
3 * INET An implementation of the TCP/IP protocol suite for the LINUX
4 * operating system. INET is implemented using the BSD Socket
5 * interface as the means of communication with the user level.
6 *
7 * The IP fragmentation functionality.
8 *
9 * Authors: Fred N. van Kempen <waltje@uWalt.NL.Mugnet.ORG>
10 * Alan Cox <alan@lxorguk.ukuu.org.uk>
11 *
12 * Fixes:
13 * Alan Cox : Split from ip.c , see ip_input.c for history.
14 * David S. Miller : Begin massive cleanup...
15 * Andi Kleen : Add sysctls.
16 * xxxx : Overlapfrag bug.
17 * Ultima : ip_expire() kernel panic.
18 * Bill Hawes : Frag accounting and evictor fixes.
19 * John McDonald : 0 length frag bug.
20 * Alexey Kuznetsov: SMP races, threading, cleanup.
21 * Patrick McHardy : LRU queue of frag heads for evictor.
22 */
23
24#define pr_fmt(fmt) "IPv4: " fmt
25
26#include <linux/compiler.h>
27#include <linux/module.h>
28#include <linux/types.h>
29#include <linux/mm.h>
30#include <linux/jiffies.h>
31#include <linux/skbuff.h>
32#include <linux/list.h>
33#include <linux/ip.h>
34#include <linux/icmp.h>
35#include <linux/netdevice.h>
36#include <linux/jhash.h>
37#include <linux/random.h>
38#include <linux/slab.h>
39#include <net/route.h>
40#include <net/dst.h>
41#include <net/sock.h>
42#include <net/ip.h>
43#include <net/icmp.h>
44#include <net/checksum.h>
45#include <net/inetpeer.h>
46#include <net/inet_frag.h>
47#include <linux/tcp.h>
48#include <linux/udp.h>
49#include <linux/inet.h>
50#include <linux/netfilter_ipv4.h>
51#include <net/inet_ecn.h>
52#include <net/l3mdev.h>
53
54/* NOTE. Logic of IP defragmentation is parallel to corresponding IPv6
55 * code now. If you change something here, _PLEASE_ update ipv6/reassembly.c
56 * as well. Or notify me, at least. --ANK
57 */
58static const char ip_frag_cache_name[] = "ip4-frags";
59
60/* Describe an entry in the "incomplete datagrams" queue. */
61struct ipq {
62 struct inet_frag_queue q;
63
64 u8 ecn; /* RFC3168 support */
65 u16 max_df_size; /* largest frag with DF set seen */
66 int iif;
67 unsigned int rid;
68 struct inet_peer *peer;
69};
70
71static u8 ip4_frag_ecn(u8 tos)
72{
73 return 1 << (tos & INET_ECN_MASK);
74}
75
76static struct inet_frags ip4_frags;
77
78static int ip_frag_reasm(struct ipq *qp, struct sk_buff *skb,
79 struct sk_buff *prev_tail, struct net_device *dev,
80 int *refs);
81
82
83static void ip4_frag_init(struct inet_frag_queue *q, const void *a)
84{
85 struct ipq *qp = container_of(q, struct ipq, q);
86 const struct frag_v4_compare_key *key = a;
87 struct net *net = q->fqdir->net;
88 struct inet_peer *p = NULL;
89
90 q->key.v4 = *key;
91 qp->ecn = 0;
92 if (q->fqdir->max_dist) {
93 rcu_read_lock();
94 p = inet_getpeer_v4(base: net->ipv4.peers, v4daddr: key->saddr, vif: key->vif);
95 if (p && !refcount_inc_not_zero(r: &p->refcnt))
96 p = NULL;
97 rcu_read_unlock();
98 }
99 qp->peer = p;
100}
101
102static void ip4_frag_free(struct inet_frag_queue *q)
103{
104 struct ipq *qp;
105
106 qp = container_of(q, struct ipq, q);
107 if (qp->peer)
108 inet_putpeer(p: qp->peer);
109}
110
111static bool frag_expire_skip_icmp(u32 user)
112{
113 return user == IP_DEFRAG_AF_PACKET ||
114 ip_defrag_user_in_between(user, lower_bond: IP_DEFRAG_CONNTRACK_IN,
115 upper_bond: __IP_DEFRAG_CONNTRACK_IN_END) ||
116 ip_defrag_user_in_between(user, lower_bond: IP_DEFRAG_CONNTRACK_BRIDGE_IN,
117 upper_bond: __IP_DEFRAG_CONNTRACK_BRIDGE_IN);
118}
119
120/*
121 * Oops, a fragment queue timed out. Kill it and send an ICMP reply.
122 */
123static void ip_expire(struct timer_list *t)
124{
125 enum skb_drop_reason reason = SKB_DROP_REASON_FRAG_REASM_TIMEOUT;
126 struct inet_frag_queue *frag = timer_container_of(frag, t, timer);
127 const struct iphdr *iph;
128 struct sk_buff *head = NULL;
129 struct net *net;
130 struct ipq *qp;
131 int refs = 1;
132
133 qp = container_of(frag, struct ipq, q);
134 net = qp->q.fqdir->net;
135
136 rcu_read_lock();
137 spin_lock(lock: &qp->q.lock);
138
139 if (qp->q.flags & INET_FRAG_COMPLETE)
140 goto out;
141
142 qp->q.flags |= INET_FRAG_DROP;
143 inet_frag_kill(q: &qp->q, refs: &refs);
144
145 /* Paired with WRITE_ONCE() in fqdir_pre_exit(). */
146 if (READ_ONCE(qp->q.fqdir->dead)) {
147 inet_frag_queue_flush(q: &qp->q, reason: 0);
148 goto out;
149 }
150
151 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
152 __IP_INC_STATS(net, IPSTATS_MIB_REASMTIMEOUT);
153
154 if (!(qp->q.flags & INET_FRAG_FIRST_IN))
155 goto out;
156
157 /* sk_buff::dev and sk_buff::rbnode are unionized. So we
158 * pull the head out of the tree in order to be able to
159 * deal with head->dev.
160 */
161 head = inet_frag_pull_head(q: &qp->q);
162 if (!head)
163 goto out;
164 head->dev = dev_get_by_index_rcu(net, ifindex: qp->iif);
165 if (!head->dev)
166 goto out;
167
168
169 /* skb has no dst, perform route lookup again */
170 iph = ip_hdr(skb: head);
171 reason = ip_route_input_noref(skb: head, daddr: iph->daddr, saddr: iph->saddr,
172 dscp: ip4h_dscp(ip4h: iph), dev: head->dev);
173 if (reason)
174 goto out;
175
176 /* Only an end host needs to send an ICMP
177 * "Fragment Reassembly Timeout" message, per RFC792.
178 */
179 reason = SKB_DROP_REASON_FRAG_REASM_TIMEOUT;
180 if (frag_expire_skip_icmp(user: qp->q.key.v4.user) &&
181 (skb_rtable(skb: head)->rt_type != RTN_LOCAL))
182 goto out;
183
184 spin_unlock(lock: &qp->q.lock);
185 icmp_send(skb_in: head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, info: 0);
186 goto out_rcu_unlock;
187
188out:
189 spin_unlock(lock: &qp->q.lock);
190out_rcu_unlock:
191 rcu_read_unlock();
192 kfree_skb_reason(skb: head, reason);
193 inet_frag_putn(q: &qp->q, refs);
194}
195
196/* Find the correct entry in the "incomplete datagrams" queue for
197 * this IP datagram, and create new one, if nothing is found.
198 */
199static struct ipq *ip_find(struct net *net, struct iphdr *iph,
200 u32 user, int vif)
201{
202 struct frag_v4_compare_key key = {
203 .saddr = iph->saddr,
204 .daddr = iph->daddr,
205 .user = user,
206 .vif = vif,
207 .id = iph->id,
208 .protocol = iph->protocol,
209 };
210 struct inet_frag_queue *q;
211
212 q = inet_frag_find(fqdir: net->ipv4.fqdir, key: &key);
213 if (!q)
214 return NULL;
215
216 return container_of(q, struct ipq, q);
217}
218
219/* Is the fragment too far ahead to be part of ipq? */
220static int ip_frag_too_far(struct ipq *qp)
221{
222 struct inet_peer *peer = qp->peer;
223 unsigned int max = qp->q.fqdir->max_dist;
224 unsigned int start, end;
225
226 int rc;
227
228 if (!peer || !max)
229 return 0;
230
231 start = qp->rid;
232 end = atomic_inc_return(v: &peer->rid);
233 qp->rid = end;
234
235 rc = qp->q.fragments_tail && (end - start) > max;
236
237 if (rc)
238 __IP_INC_STATS(qp->q.fqdir->net, IPSTATS_MIB_REASMFAILS);
239
240 return rc;
241}
242
243static int ip_frag_reinit(struct ipq *qp)
244{
245 if (!mod_timer_pending(timer: &qp->q.timer, expires: jiffies + qp->q.fqdir->timeout))
246 return -ETIMEDOUT;
247
248 inet_frag_queue_flush(q: &qp->q, reason: SKB_DROP_REASON_FRAG_TOO_FAR);
249
250 qp->q.flags = 0;
251 qp->q.len = 0;
252 qp->q.meat = 0;
253 qp->q.rb_fragments = RB_ROOT;
254 qp->q.fragments_tail = NULL;
255 qp->q.last_run_head = NULL;
256 qp->iif = 0;
257 qp->ecn = 0;
258
259 return 0;
260}
261
262/* Add new segment to existing queue. */
263static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb, int *refs)
264{
265 struct net *net = qp->q.fqdir->net;
266 int ihl, end, flags, offset;
267 struct sk_buff *prev_tail;
268 struct net_device *dev;
269 unsigned int fragsize;
270 int err = -ENOENT;
271 SKB_DR(reason);
272 u8 ecn;
273
274 /* If reassembly is already done, @skb must be a duplicate frag. */
275 if (qp->q.flags & INET_FRAG_COMPLETE) {
276 SKB_DR_SET(reason, DUP_FRAG);
277 goto err;
278 }
279
280 if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) &&
281 unlikely(ip_frag_too_far(qp)) &&
282 unlikely(err = ip_frag_reinit(qp))) {
283 inet_frag_kill(q: &qp->q, refs);
284 goto err;
285 }
286
287 ecn = ip4_frag_ecn(tos: ip_hdr(skb)->tos);
288 offset = ntohs(ip_hdr(skb)->frag_off);
289 flags = offset & ~IP_OFFSET;
290 offset &= IP_OFFSET;
291 offset <<= 3; /* offset is in 8-byte chunks */
292 ihl = ip_hdrlen(skb);
293
294 /* Determine the position of this fragment. */
295 end = offset + skb->len - skb_network_offset(skb) - ihl;
296 err = -EINVAL;
297
298 /* Is this the final fragment? */
299 if ((flags & IP_MF) == 0) {
300 /* If we already have some bits beyond end
301 * or have different end, the segment is corrupted.
302 */
303 if (end < qp->q.len ||
304 ((qp->q.flags & INET_FRAG_LAST_IN) && end != qp->q.len))
305 goto discard_qp;
306 qp->q.flags |= INET_FRAG_LAST_IN;
307 qp->q.len = end;
308 } else {
309 if (end&7) {
310 end &= ~7;
311 if (skb->ip_summed != CHECKSUM_UNNECESSARY)
312 skb->ip_summed = CHECKSUM_NONE;
313 }
314 if (end > qp->q.len) {
315 /* Some bits beyond end -> corruption. */
316 if (qp->q.flags & INET_FRAG_LAST_IN)
317 goto discard_qp;
318 qp->q.len = end;
319 }
320 }
321 if (end == offset)
322 goto discard_qp;
323
324 err = -ENOMEM;
325 if (!pskb_pull(skb, len: skb_network_offset(skb) + ihl))
326 goto discard_qp;
327
328 err = pskb_trim_rcsum(skb, len: end - offset);
329 if (err)
330 goto discard_qp;
331
332 /* Note : skb->rbnode and skb->dev share the same location. */
333 dev = skb->dev;
334 /* Makes sure compiler wont do silly aliasing games */
335 barrier();
336
337 prev_tail = qp->q.fragments_tail;
338 err = inet_frag_queue_insert(q: &qp->q, skb, offset, end);
339 if (err)
340 goto insert_error;
341
342 if (dev)
343 qp->iif = dev->ifindex;
344
345 qp->q.stamp = skb->tstamp;
346 qp->q.tstamp_type = skb->tstamp_type;
347 qp->q.meat += skb->len;
348 qp->ecn |= ecn;
349 add_frag_mem_limit(fqdir: qp->q.fqdir, val: skb->truesize);
350 if (offset == 0)
351 qp->q.flags |= INET_FRAG_FIRST_IN;
352
353 fragsize = skb->len + ihl;
354
355 if (fragsize > qp->q.max_size)
356 qp->q.max_size = fragsize;
357
358 if (ip_hdr(skb)->frag_off & htons(IP_DF) &&
359 fragsize > qp->max_df_size)
360 qp->max_df_size = fragsize;
361
362 if (qp->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
363 qp->q.meat == qp->q.len) {
364 unsigned long orefdst = skb->_skb_refdst;
365
366 skb->_skb_refdst = 0UL;
367 err = ip_frag_reasm(qp, skb, prev_tail, dev, refs);
368 skb->_skb_refdst = orefdst;
369 if (err)
370 inet_frag_kill(q: &qp->q, refs);
371 return err;
372 }
373
374 skb_dst_drop(skb);
375 skb_orphan(skb);
376 return -EINPROGRESS;
377
378insert_error:
379 if (err == IPFRAG_DUP) {
380 SKB_DR_SET(reason, DUP_FRAG);
381 err = -EINVAL;
382 goto err;
383 }
384 err = -EINVAL;
385 __IP_INC_STATS(net, IPSTATS_MIB_REASM_OVERLAPS);
386discard_qp:
387 inet_frag_kill(q: &qp->q, refs);
388 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
389err:
390 kfree_skb_reason(skb, reason);
391 return err;
392}
393
394static bool ip_frag_coalesce_ok(const struct ipq *qp)
395{
396 return qp->q.key.v4.user == IP_DEFRAG_LOCAL_DELIVER;
397}
398
399/* Build a new IP datagram from all its fragments. */
400static int ip_frag_reasm(struct ipq *qp, struct sk_buff *skb,
401 struct sk_buff *prev_tail, struct net_device *dev,
402 int *refs)
403{
404 struct net *net = qp->q.fqdir->net;
405 struct iphdr *iph;
406 void *reasm_data;
407 int len, err;
408 u8 ecn;
409
410 inet_frag_kill(q: &qp->q, refs);
411
412 ecn = ip_frag_ecn_table[qp->ecn];
413 if (unlikely(ecn == 0xff)) {
414 err = -EINVAL;
415 goto out_fail;
416 }
417
418 /* Make the one we just received the head. */
419 reasm_data = inet_frag_reasm_prepare(q: &qp->q, skb, parent: prev_tail);
420 if (!reasm_data)
421 goto out_nomem;
422
423 len = ip_hdrlen(skb) + qp->q.len;
424 err = -E2BIG;
425 if (len > 65535)
426 goto out_oversize;
427
428 inet_frag_reasm_finish(q: &qp->q, head: skb, reasm_data,
429 try_coalesce: ip_frag_coalesce_ok(qp));
430
431 skb->dev = dev;
432 IPCB(skb)->frag_max_size = max(qp->max_df_size, qp->q.max_size);
433
434 iph = ip_hdr(skb);
435 iph->tot_len = htons(len);
436 iph->tos |= ecn;
437
438 /* When we set IP_DF on a refragmented skb we must also force a
439 * call to ip_fragment to avoid forwarding a DF-skb of size s while
440 * original sender only sent fragments of size f (where f < s).
441 *
442 * We only set DF/IPSKB_FRAG_PMTU if such DF fragment was the largest
443 * frag seen to avoid sending tiny DF-fragments in case skb was built
444 * from one very small df-fragment and one large non-df frag.
445 */
446 if (qp->max_df_size == qp->q.max_size) {
447 IPCB(skb)->flags |= IPSKB_FRAG_PMTU;
448 iph->frag_off = htons(IP_DF);
449 } else {
450 iph->frag_off = 0;
451 }
452
453 ip_send_check(ip: iph);
454
455 __IP_INC_STATS(net, IPSTATS_MIB_REASMOKS);
456 qp->q.rb_fragments = RB_ROOT;
457 qp->q.fragments_tail = NULL;
458 qp->q.last_run_head = NULL;
459 return 0;
460
461out_nomem:
462 net_dbg_ratelimited("queue_glue: no memory for gluing queue %p\n", qp);
463 err = -ENOMEM;
464 goto out_fail;
465out_oversize:
466 net_info_ratelimited("Oversized IP packet from %pI4\n", &qp->q.key.v4.saddr);
467out_fail:
468 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
469 return err;
470}
471
472/* Process an incoming IP datagram fragment. */
473int ip_defrag(struct net *net, struct sk_buff *skb, u32 user)
474{
475 struct net_device *dev;
476 struct ipq *qp;
477 int vif;
478
479 __IP_INC_STATS(net, IPSTATS_MIB_REASMREQDS);
480
481 /* Lookup (or create) queue header */
482 rcu_read_lock();
483 dev = skb->dev ? : skb_dst_dev_rcu(skb);
484 vif = l3mdev_master_ifindex_rcu(dev);
485 qp = ip_find(net, iph: ip_hdr(skb), user, vif);
486 if (qp) {
487 int ret, refs = 0;
488
489 spin_lock(lock: &qp->q.lock);
490
491 ret = ip_frag_queue(qp, skb, refs: &refs);
492
493 spin_unlock(lock: &qp->q.lock);
494 rcu_read_unlock();
495 inet_frag_putn(q: &qp->q, refs);
496 return ret;
497 }
498 rcu_read_unlock();
499
500 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
501 kfree_skb(skb);
502 return -ENOMEM;
503}
504EXPORT_SYMBOL(ip_defrag);
505
506struct sk_buff *ip_check_defrag(struct net *net, struct sk_buff *skb, u32 user)
507{
508 struct iphdr iph;
509 int netoff;
510 u32 len;
511
512 if (skb->protocol != htons(ETH_P_IP))
513 return skb;
514
515 netoff = skb_network_offset(skb);
516
517 if (skb_copy_bits(skb, offset: netoff, to: &iph, len: sizeof(iph)) < 0)
518 return skb;
519
520 if (iph.ihl < 5 || iph.version != 4)
521 return skb;
522
523 len = ntohs(iph.tot_len);
524 if (skb->len < netoff + len || len < (iph.ihl * 4))
525 return skb;
526
527 if (ip_is_fragment(iph: &iph)) {
528 skb = skb_share_check(skb, GFP_ATOMIC);
529 if (skb) {
530 if (!pskb_may_pull(skb, len: netoff + iph.ihl * 4)) {
531 kfree_skb(skb);
532 return NULL;
533 }
534 if (pskb_trim_rcsum(skb, len: netoff + len)) {
535 kfree_skb(skb);
536 return NULL;
537 }
538 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
539 if (ip_defrag(net, skb, user))
540 return NULL;
541 skb_clear_hash(skb);
542 }
543 }
544 return skb;
545}
546EXPORT_SYMBOL(ip_check_defrag);
547
548#ifdef CONFIG_SYSCTL
549static int dist_min;
550
551static struct ctl_table ip4_frags_ns_ctl_table[] = {
552 {
553 .procname = "ipfrag_high_thresh",
554 .maxlen = sizeof(unsigned long),
555 .mode = 0644,
556 .proc_handler = proc_doulongvec_minmax,
557 },
558 {
559 .procname = "ipfrag_low_thresh",
560 .maxlen = sizeof(unsigned long),
561 .mode = 0644,
562 .proc_handler = proc_doulongvec_minmax,
563 },
564 {
565 .procname = "ipfrag_time",
566 .maxlen = sizeof(int),
567 .mode = 0644,
568 .proc_handler = proc_dointvec_jiffies,
569 },
570 {
571 .procname = "ipfrag_max_dist",
572 .maxlen = sizeof(int),
573 .mode = 0644,
574 .proc_handler = proc_dointvec_minmax,
575 .extra1 = &dist_min,
576 },
577};
578
579/* secret interval has been deprecated */
580static int ip4_frags_secret_interval_unused;
581static struct ctl_table ip4_frags_ctl_table[] = {
582 {
583 .procname = "ipfrag_secret_interval",
584 .data = &ip4_frags_secret_interval_unused,
585 .maxlen = sizeof(int),
586 .mode = 0644,
587 .proc_handler = proc_dointvec_jiffies,
588 },
589};
590
591static int __net_init ip4_frags_ns_ctl_register(struct net *net)
592{
593 struct ctl_table *table;
594 struct ctl_table_header *hdr;
595
596 table = ip4_frags_ns_ctl_table;
597 if (!net_eq(net1: net, net2: &init_net)) {
598 table = kmemdup(table, sizeof(ip4_frags_ns_ctl_table), GFP_KERNEL);
599 if (!table)
600 goto err_alloc;
601
602 }
603 table[0].data = &net->ipv4.fqdir->high_thresh;
604 table[0].extra1 = &net->ipv4.fqdir->low_thresh;
605 table[1].data = &net->ipv4.fqdir->low_thresh;
606 table[1].extra2 = &net->ipv4.fqdir->high_thresh;
607 table[2].data = &net->ipv4.fqdir->timeout;
608 table[3].data = &net->ipv4.fqdir->max_dist;
609
610 hdr = register_net_sysctl_sz(net, path: "net/ipv4", table,
611 ARRAY_SIZE(ip4_frags_ns_ctl_table));
612 if (!hdr)
613 goto err_reg;
614
615 net->ipv4.frags_hdr = hdr;
616 return 0;
617
618err_reg:
619 if (!net_eq(net1: net, net2: &init_net))
620 kfree(objp: table);
621err_alloc:
622 return -ENOMEM;
623}
624
625static void __net_exit ip4_frags_ns_ctl_unregister(struct net *net)
626{
627 const struct ctl_table *table;
628
629 table = net->ipv4.frags_hdr->ctl_table_arg;
630 unregister_net_sysctl_table(header: net->ipv4.frags_hdr);
631 kfree(objp: table);
632}
633
634static void __init ip4_frags_ctl_register(void)
635{
636 register_net_sysctl(&init_net, "net/ipv4", ip4_frags_ctl_table);
637}
638#else
639static int ip4_frags_ns_ctl_register(struct net *net)
640{
641 return 0;
642}
643
644static void ip4_frags_ns_ctl_unregister(struct net *net)
645{
646}
647
648static void __init ip4_frags_ctl_register(void)
649{
650}
651#endif
652
653static int __net_init ipv4_frags_init_net(struct net *net)
654{
655 int res;
656
657 res = fqdir_init(fqdirp: &net->ipv4.fqdir, f: &ip4_frags, net);
658 if (res < 0)
659 return res;
660 /* Fragment cache limits.
661 *
662 * The fragment memory accounting code, (tries to) account for
663 * the real memory usage, by measuring both the size of frag
664 * queue struct (inet_frag_queue (ipv4:ipq/ipv6:frag_queue))
665 * and the SKB's truesize.
666 *
667 * A 64K fragment consumes 129736 bytes (44*2944)+200
668 * (1500 truesize == 2944, sizeof(struct ipq) == 200)
669 *
670 * We will commit 4MB at one time. Should we cross that limit
671 * we will prune down to 3MB, making room for approx 8 big 64K
672 * fragments 8x128k.
673 */
674 net->ipv4.fqdir->high_thresh = 4 * 1024 * 1024;
675 net->ipv4.fqdir->low_thresh = 3 * 1024 * 1024;
676 /*
677 * Important NOTE! Fragment queue must be destroyed before MSL expires.
678 * RFC791 is wrong proposing to prolongate timer each fragment arrival
679 * by TTL.
680 */
681 net->ipv4.fqdir->timeout = IP_FRAG_TIME;
682
683 net->ipv4.fqdir->max_dist = 64;
684
685 res = ip4_frags_ns_ctl_register(net);
686 if (res < 0)
687 fqdir_exit(fqdir: net->ipv4.fqdir);
688 return res;
689}
690
691static void __net_exit ipv4_frags_pre_exit_net(struct net *net)
692{
693 fqdir_pre_exit(fqdir: net->ipv4.fqdir);
694}
695
696static void __net_exit ipv4_frags_exit_net(struct net *net)
697{
698 ip4_frags_ns_ctl_unregister(net);
699 fqdir_exit(fqdir: net->ipv4.fqdir);
700}
701
702static struct pernet_operations ip4_frags_ops = {
703 .init = ipv4_frags_init_net,
704 .pre_exit = ipv4_frags_pre_exit_net,
705 .exit = ipv4_frags_exit_net,
706};
707
708
709static u32 ip4_key_hashfn(const void *data, u32 len, u32 seed)
710{
711 return jhash2(k: data,
712 length: sizeof(struct frag_v4_compare_key) / sizeof(u32), initval: seed);
713}
714
715static u32 ip4_obj_hashfn(const void *data, u32 len, u32 seed)
716{
717 const struct inet_frag_queue *fq = data;
718
719 return jhash2(k: (const u32 *)&fq->key.v4,
720 length: sizeof(struct frag_v4_compare_key) / sizeof(u32), initval: seed);
721}
722
723static int ip4_obj_cmpfn(struct rhashtable_compare_arg *arg, const void *ptr)
724{
725 const struct frag_v4_compare_key *key = arg->key;
726 const struct inet_frag_queue *fq = ptr;
727
728 return !!memcmp(p: &fq->key, q: key, size: sizeof(*key));
729}
730
731static const struct rhashtable_params ip4_rhash_params = {
732 .head_offset = offsetof(struct inet_frag_queue, node),
733 .key_offset = offsetof(struct inet_frag_queue, key),
734 .key_len = sizeof(struct frag_v4_compare_key),
735 .hashfn = ip4_key_hashfn,
736 .obj_hashfn = ip4_obj_hashfn,
737 .obj_cmpfn = ip4_obj_cmpfn,
738 .automatic_shrinking = true,
739};
740
741void __init ipfrag_init(void)
742{
743 ip4_frags.constructor = ip4_frag_init;
744 ip4_frags.destructor = ip4_frag_free;
745 ip4_frags.qsize = sizeof(struct ipq);
746 ip4_frags.frag_expire = ip_expire;
747 ip4_frags.frags_cache_name = ip_frag_cache_name;
748 ip4_frags.rhash_params = ip4_rhash_params;
749 if (inet_frags_init(&ip4_frags))
750 panic(fmt: "IP: failed to allocate ip4_frags cache\n");
751 ip4_frags_ctl_register();
752 register_pernet_subsys(&ip4_frags_ops);
753}
754

source code of linux/net/ipv4/ip_fragment.c