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
81
82static void ip4_frag_init(struct inet_frag_queue *q, const void *a)
83{
84 struct ipq *qp = container_of(q, struct ipq, q);
85 struct net *net = q->fqdir->net;
86
87 const struct frag_v4_compare_key *key = a;
88
89 q->key.v4 = *key;
90 qp->ecn = 0;
91 qp->peer = q->fqdir->max_dist ?
92 inet_getpeer_v4(base: net->ipv4.peers, v4daddr: key->saddr, vif: key->vif, create: 1) :
93 NULL;
94}
95
96static void ip4_frag_free(struct inet_frag_queue *q)
97{
98 struct ipq *qp;
99
100 qp = container_of(q, struct ipq, q);
101 if (qp->peer)
102 inet_putpeer(p: qp->peer);
103}
104
105
106/* Destruction primitives. */
107
108static void ipq_put(struct ipq *ipq)
109{
110 inet_frag_put(q: &ipq->q);
111}
112
113/* Kill ipq entry. It is not destroyed immediately,
114 * because caller (and someone more) holds reference count.
115 */
116static void ipq_kill(struct ipq *ipq)
117{
118 inet_frag_kill(q: &ipq->q);
119}
120
121static bool frag_expire_skip_icmp(u32 user)
122{
123 return user == IP_DEFRAG_AF_PACKET ||
124 ip_defrag_user_in_between(user, lower_bond: IP_DEFRAG_CONNTRACK_IN,
125 upper_bond: __IP_DEFRAG_CONNTRACK_IN_END) ||
126 ip_defrag_user_in_between(user, lower_bond: IP_DEFRAG_CONNTRACK_BRIDGE_IN,
127 upper_bond: __IP_DEFRAG_CONNTRACK_BRIDGE_IN);
128}
129
130/*
131 * Oops, a fragment queue timed out. Kill it and send an ICMP reply.
132 */
133static void ip_expire(struct timer_list *t)
134{
135 struct inet_frag_queue *frag = from_timer(frag, t, timer);
136 const struct iphdr *iph;
137 struct sk_buff *head = NULL;
138 struct net *net;
139 struct ipq *qp;
140 int err;
141
142 qp = container_of(frag, struct ipq, q);
143 net = qp->q.fqdir->net;
144
145 rcu_read_lock();
146
147 /* Paired with WRITE_ONCE() in fqdir_pre_exit(). */
148 if (READ_ONCE(qp->q.fqdir->dead))
149 goto out_rcu_unlock;
150
151 spin_lock(lock: &qp->q.lock);
152
153 if (qp->q.flags & INET_FRAG_COMPLETE)
154 goto out;
155
156 qp->q.flags |= INET_FRAG_DROP;
157 ipq_kill(ipq: qp);
158 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
159 __IP_INC_STATS(net, IPSTATS_MIB_REASMTIMEOUT);
160
161 if (!(qp->q.flags & INET_FRAG_FIRST_IN))
162 goto out;
163
164 /* sk_buff::dev and sk_buff::rbnode are unionized. So we
165 * pull the head out of the tree in order to be able to
166 * deal with head->dev.
167 */
168 head = inet_frag_pull_head(q: &qp->q);
169 if (!head)
170 goto out;
171 head->dev = dev_get_by_index_rcu(net, ifindex: qp->iif);
172 if (!head->dev)
173 goto out;
174
175
176 /* skb has no dst, perform route lookup again */
177 iph = ip_hdr(skb: head);
178 err = ip_route_input_noref(skb: head, dst: iph->daddr, src: iph->saddr,
179 tos: iph->tos, devin: head->dev);
180 if (err)
181 goto out;
182
183 /* Only an end host needs to send an ICMP
184 * "Fragment Reassembly Timeout" message, per RFC792.
185 */
186 if (frag_expire_skip_icmp(user: qp->q.key.v4.user) &&
187 (skb_rtable(skb: head)->rt_type != RTN_LOCAL))
188 goto out;
189
190 spin_unlock(lock: &qp->q.lock);
191 icmp_send(skb_in: head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, info: 0);
192 goto out_rcu_unlock;
193
194out:
195 spin_unlock(lock: &qp->q.lock);
196out_rcu_unlock:
197 rcu_read_unlock();
198 kfree_skb_reason(skb: head, reason: SKB_DROP_REASON_FRAG_REASM_TIMEOUT);
199 ipq_put(ipq: qp);
200}
201
202/* Find the correct entry in the "incomplete datagrams" queue for
203 * this IP datagram, and create new one, if nothing is found.
204 */
205static struct ipq *ip_find(struct net *net, struct iphdr *iph,
206 u32 user, int vif)
207{
208 struct frag_v4_compare_key key = {
209 .saddr = iph->saddr,
210 .daddr = iph->daddr,
211 .user = user,
212 .vif = vif,
213 .id = iph->id,
214 .protocol = iph->protocol,
215 };
216 struct inet_frag_queue *q;
217
218 q = inet_frag_find(fqdir: net->ipv4.fqdir, key: &key);
219 if (!q)
220 return NULL;
221
222 return container_of(q, struct ipq, q);
223}
224
225/* Is the fragment too far ahead to be part of ipq? */
226static int ip_frag_too_far(struct ipq *qp)
227{
228 struct inet_peer *peer = qp->peer;
229 unsigned int max = qp->q.fqdir->max_dist;
230 unsigned int start, end;
231
232 int rc;
233
234 if (!peer || !max)
235 return 0;
236
237 start = qp->rid;
238 end = atomic_inc_return(v: &peer->rid);
239 qp->rid = end;
240
241 rc = qp->q.fragments_tail && (end - start) > max;
242
243 if (rc)
244 __IP_INC_STATS(qp->q.fqdir->net, IPSTATS_MIB_REASMFAILS);
245
246 return rc;
247}
248
249static int ip_frag_reinit(struct ipq *qp)
250{
251 unsigned int sum_truesize = 0;
252
253 if (!mod_timer(timer: &qp->q.timer, expires: jiffies + qp->q.fqdir->timeout)) {
254 refcount_inc(r: &qp->q.refcnt);
255 return -ETIMEDOUT;
256 }
257
258 sum_truesize = inet_frag_rbtree_purge(root: &qp->q.rb_fragments,
259 reason: SKB_DROP_REASON_FRAG_TOO_FAR);
260 sub_frag_mem_limit(fqdir: qp->q.fqdir, val: sum_truesize);
261
262 qp->q.flags = 0;
263 qp->q.len = 0;
264 qp->q.meat = 0;
265 qp->q.rb_fragments = RB_ROOT;
266 qp->q.fragments_tail = NULL;
267 qp->q.last_run_head = NULL;
268 qp->iif = 0;
269 qp->ecn = 0;
270
271 return 0;
272}
273
274/* Add new segment to existing queue. */
275static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
276{
277 struct net *net = qp->q.fqdir->net;
278 int ihl, end, flags, offset;
279 struct sk_buff *prev_tail;
280 struct net_device *dev;
281 unsigned int fragsize;
282 int err = -ENOENT;
283 SKB_DR(reason);
284 u8 ecn;
285
286 /* If reassembly is already done, @skb must be a duplicate frag. */
287 if (qp->q.flags & INET_FRAG_COMPLETE) {
288 SKB_DR_SET(reason, DUP_FRAG);
289 goto err;
290 }
291
292 if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) &&
293 unlikely(ip_frag_too_far(qp)) &&
294 unlikely(err = ip_frag_reinit(qp))) {
295 ipq_kill(ipq: qp);
296 goto err;
297 }
298
299 ecn = ip4_frag_ecn(tos: ip_hdr(skb)->tos);
300 offset = ntohs(ip_hdr(skb)->frag_off);
301 flags = offset & ~IP_OFFSET;
302 offset &= IP_OFFSET;
303 offset <<= 3; /* offset is in 8-byte chunks */
304 ihl = ip_hdrlen(skb);
305
306 /* Determine the position of this fragment. */
307 end = offset + skb->len - skb_network_offset(skb) - ihl;
308 err = -EINVAL;
309
310 /* Is this the final fragment? */
311 if ((flags & IP_MF) == 0) {
312 /* If we already have some bits beyond end
313 * or have different end, the segment is corrupted.
314 */
315 if (end < qp->q.len ||
316 ((qp->q.flags & INET_FRAG_LAST_IN) && end != qp->q.len))
317 goto discard_qp;
318 qp->q.flags |= INET_FRAG_LAST_IN;
319 qp->q.len = end;
320 } else {
321 if (end&7) {
322 end &= ~7;
323 if (skb->ip_summed != CHECKSUM_UNNECESSARY)
324 skb->ip_summed = CHECKSUM_NONE;
325 }
326 if (end > qp->q.len) {
327 /* Some bits beyond end -> corruption. */
328 if (qp->q.flags & INET_FRAG_LAST_IN)
329 goto discard_qp;
330 qp->q.len = end;
331 }
332 }
333 if (end == offset)
334 goto discard_qp;
335
336 err = -ENOMEM;
337 if (!pskb_pull(skb, len: skb_network_offset(skb) + ihl))
338 goto discard_qp;
339
340 err = pskb_trim_rcsum(skb, len: end - offset);
341 if (err)
342 goto discard_qp;
343
344 /* Note : skb->rbnode and skb->dev share the same location. */
345 dev = skb->dev;
346 /* Makes sure compiler wont do silly aliasing games */
347 barrier();
348
349 prev_tail = qp->q.fragments_tail;
350 err = inet_frag_queue_insert(q: &qp->q, skb, offset, end);
351 if (err)
352 goto insert_error;
353
354 if (dev)
355 qp->iif = dev->ifindex;
356
357 qp->q.stamp = skb->tstamp;
358 qp->q.mono_delivery_time = skb->mono_delivery_time;
359 qp->q.meat += skb->len;
360 qp->ecn |= ecn;
361 add_frag_mem_limit(fqdir: qp->q.fqdir, val: skb->truesize);
362 if (offset == 0)
363 qp->q.flags |= INET_FRAG_FIRST_IN;
364
365 fragsize = skb->len + ihl;
366
367 if (fragsize > qp->q.max_size)
368 qp->q.max_size = fragsize;
369
370 if (ip_hdr(skb)->frag_off & htons(IP_DF) &&
371 fragsize > qp->max_df_size)
372 qp->max_df_size = fragsize;
373
374 if (qp->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
375 qp->q.meat == qp->q.len) {
376 unsigned long orefdst = skb->_skb_refdst;
377
378 skb->_skb_refdst = 0UL;
379 err = ip_frag_reasm(qp, skb, prev_tail, dev);
380 skb->_skb_refdst = orefdst;
381 if (err)
382 inet_frag_kill(q: &qp->q);
383 return err;
384 }
385
386 skb_dst_drop(skb);
387 skb_orphan(skb);
388 return -EINPROGRESS;
389
390insert_error:
391 if (err == IPFRAG_DUP) {
392 SKB_DR_SET(reason, DUP_FRAG);
393 err = -EINVAL;
394 goto err;
395 }
396 err = -EINVAL;
397 __IP_INC_STATS(net, IPSTATS_MIB_REASM_OVERLAPS);
398discard_qp:
399 inet_frag_kill(q: &qp->q);
400 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
401err:
402 kfree_skb_reason(skb, reason);
403 return err;
404}
405
406static bool ip_frag_coalesce_ok(const struct ipq *qp)
407{
408 return qp->q.key.v4.user == IP_DEFRAG_LOCAL_DELIVER;
409}
410
411/* Build a new IP datagram from all its fragments. */
412static int ip_frag_reasm(struct ipq *qp, struct sk_buff *skb,
413 struct sk_buff *prev_tail, struct net_device *dev)
414{
415 struct net *net = qp->q.fqdir->net;
416 struct iphdr *iph;
417 void *reasm_data;
418 int len, err;
419 u8 ecn;
420
421 ipq_kill(ipq: qp);
422
423 ecn = ip_frag_ecn_table[qp->ecn];
424 if (unlikely(ecn == 0xff)) {
425 err = -EINVAL;
426 goto out_fail;
427 }
428
429 /* Make the one we just received the head. */
430 reasm_data = inet_frag_reasm_prepare(q: &qp->q, skb, parent: prev_tail);
431 if (!reasm_data)
432 goto out_nomem;
433
434 len = ip_hdrlen(skb) + qp->q.len;
435 err = -E2BIG;
436 if (len > 65535)
437 goto out_oversize;
438
439 inet_frag_reasm_finish(q: &qp->q, head: skb, reasm_data,
440 try_coalesce: ip_frag_coalesce_ok(qp));
441
442 skb->dev = dev;
443 IPCB(skb)->frag_max_size = max(qp->max_df_size, qp->q.max_size);
444
445 iph = ip_hdr(skb);
446 iph->tot_len = htons(len);
447 iph->tos |= ecn;
448
449 /* When we set IP_DF on a refragmented skb we must also force a
450 * call to ip_fragment to avoid forwarding a DF-skb of size s while
451 * original sender only sent fragments of size f (where f < s).
452 *
453 * We only set DF/IPSKB_FRAG_PMTU if such DF fragment was the largest
454 * frag seen to avoid sending tiny DF-fragments in case skb was built
455 * from one very small df-fragment and one large non-df frag.
456 */
457 if (qp->max_df_size == qp->q.max_size) {
458 IPCB(skb)->flags |= IPSKB_FRAG_PMTU;
459 iph->frag_off = htons(IP_DF);
460 } else {
461 iph->frag_off = 0;
462 }
463
464 ip_send_check(ip: iph);
465
466 __IP_INC_STATS(net, IPSTATS_MIB_REASMOKS);
467 qp->q.rb_fragments = RB_ROOT;
468 qp->q.fragments_tail = NULL;
469 qp->q.last_run_head = NULL;
470 return 0;
471
472out_nomem:
473 net_dbg_ratelimited("queue_glue: no memory for gluing queue %p\n", qp);
474 err = -ENOMEM;
475 goto out_fail;
476out_oversize:
477 net_info_ratelimited("Oversized IP packet from %pI4\n", &qp->q.key.v4.saddr);
478out_fail:
479 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
480 return err;
481}
482
483/* Process an incoming IP datagram fragment. */
484int ip_defrag(struct net *net, struct sk_buff *skb, u32 user)
485{
486 struct net_device *dev = skb->dev ? : skb_dst(skb)->dev;
487 int vif = l3mdev_master_ifindex_rcu(dev);
488 struct ipq *qp;
489
490 __IP_INC_STATS(net, IPSTATS_MIB_REASMREQDS);
491
492 /* Lookup (or create) queue header */
493 qp = ip_find(net, iph: ip_hdr(skb), user, vif);
494 if (qp) {
495 int ret;
496
497 spin_lock(lock: &qp->q.lock);
498
499 ret = ip_frag_queue(qp, skb);
500
501 spin_unlock(lock: &qp->q.lock);
502 ipq_put(ipq: qp);
503 return ret;
504 }
505
506 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
507 kfree_skb(skb);
508 return -ENOMEM;
509}
510EXPORT_SYMBOL(ip_defrag);
511
512struct sk_buff *ip_check_defrag(struct net *net, struct sk_buff *skb, u32 user)
513{
514 struct iphdr iph;
515 int netoff;
516 u32 len;
517
518 if (skb->protocol != htons(ETH_P_IP))
519 return skb;
520
521 netoff = skb_network_offset(skb);
522
523 if (skb_copy_bits(skb, offset: netoff, to: &iph, len: sizeof(iph)) < 0)
524 return skb;
525
526 if (iph.ihl < 5 || iph.version != 4)
527 return skb;
528
529 len = ntohs(iph.tot_len);
530 if (skb->len < netoff + len || len < (iph.ihl * 4))
531 return skb;
532
533 if (ip_is_fragment(iph: &iph)) {
534 skb = skb_share_check(skb, GFP_ATOMIC);
535 if (skb) {
536 if (!pskb_may_pull(skb, len: netoff + iph.ihl * 4)) {
537 kfree_skb(skb);
538 return NULL;
539 }
540 if (pskb_trim_rcsum(skb, len: netoff + len)) {
541 kfree_skb(skb);
542 return NULL;
543 }
544 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
545 if (ip_defrag(net, skb, user))
546 return NULL;
547 skb_clear_hash(skb);
548 }
549 }
550 return skb;
551}
552EXPORT_SYMBOL(ip_check_defrag);
553
554#ifdef CONFIG_SYSCTL
555static int dist_min;
556
557static struct ctl_table ip4_frags_ns_ctl_table[] = {
558 {
559 .procname = "ipfrag_high_thresh",
560 .maxlen = sizeof(unsigned long),
561 .mode = 0644,
562 .proc_handler = proc_doulongvec_minmax,
563 },
564 {
565 .procname = "ipfrag_low_thresh",
566 .maxlen = sizeof(unsigned long),
567 .mode = 0644,
568 .proc_handler = proc_doulongvec_minmax,
569 },
570 {
571 .procname = "ipfrag_time",
572 .maxlen = sizeof(int),
573 .mode = 0644,
574 .proc_handler = proc_dointvec_jiffies,
575 },
576 {
577 .procname = "ipfrag_max_dist",
578 .maxlen = sizeof(int),
579 .mode = 0644,
580 .proc_handler = proc_dointvec_minmax,
581 .extra1 = &dist_min,
582 },
583 { }
584};
585
586/* secret interval has been deprecated */
587static int ip4_frags_secret_interval_unused;
588static struct ctl_table ip4_frags_ctl_table[] = {
589 {
590 .procname = "ipfrag_secret_interval",
591 .data = &ip4_frags_secret_interval_unused,
592 .maxlen = sizeof(int),
593 .mode = 0644,
594 .proc_handler = proc_dointvec_jiffies,
595 },
596 { }
597};
598
599static int __net_init ip4_frags_ns_ctl_register(struct net *net)
600{
601 struct ctl_table *table;
602 struct ctl_table_header *hdr;
603
604 table = ip4_frags_ns_ctl_table;
605 if (!net_eq(net1: net, net2: &init_net)) {
606 table = kmemdup(p: table, size: sizeof(ip4_frags_ns_ctl_table), GFP_KERNEL);
607 if (!table)
608 goto err_alloc;
609
610 }
611 table[0].data = &net->ipv4.fqdir->high_thresh;
612 table[0].extra1 = &net->ipv4.fqdir->low_thresh;
613 table[1].data = &net->ipv4.fqdir->low_thresh;
614 table[1].extra2 = &net->ipv4.fqdir->high_thresh;
615 table[2].data = &net->ipv4.fqdir->timeout;
616 table[3].data = &net->ipv4.fqdir->max_dist;
617
618 hdr = register_net_sysctl_sz(net, path: "net/ipv4", table,
619 ARRAY_SIZE(ip4_frags_ns_ctl_table));
620 if (!hdr)
621 goto err_reg;
622
623 net->ipv4.frags_hdr = hdr;
624 return 0;
625
626err_reg:
627 if (!net_eq(net1: net, net2: &init_net))
628 kfree(objp: table);
629err_alloc:
630 return -ENOMEM;
631}
632
633static void __net_exit ip4_frags_ns_ctl_unregister(struct net *net)
634{
635 struct ctl_table *table;
636
637 table = net->ipv4.frags_hdr->ctl_table_arg;
638 unregister_net_sysctl_table(header: net->ipv4.frags_hdr);
639 kfree(objp: table);
640}
641
642static void __init ip4_frags_ctl_register(void)
643{
644 register_net_sysctl(&init_net, "net/ipv4", ip4_frags_ctl_table);
645}
646#else
647static int ip4_frags_ns_ctl_register(struct net *net)
648{
649 return 0;
650}
651
652static void ip4_frags_ns_ctl_unregister(struct net *net)
653{
654}
655
656static void __init ip4_frags_ctl_register(void)
657{
658}
659#endif
660
661static int __net_init ipv4_frags_init_net(struct net *net)
662{
663 int res;
664
665 res = fqdir_init(fqdirp: &net->ipv4.fqdir, f: &ip4_frags, net);
666 if (res < 0)
667 return res;
668 /* Fragment cache limits.
669 *
670 * The fragment memory accounting code, (tries to) account for
671 * the real memory usage, by measuring both the size of frag
672 * queue struct (inet_frag_queue (ipv4:ipq/ipv6:frag_queue))
673 * and the SKB's truesize.
674 *
675 * A 64K fragment consumes 129736 bytes (44*2944)+200
676 * (1500 truesize == 2944, sizeof(struct ipq) == 200)
677 *
678 * We will commit 4MB at one time. Should we cross that limit
679 * we will prune down to 3MB, making room for approx 8 big 64K
680 * fragments 8x128k.
681 */
682 net->ipv4.fqdir->high_thresh = 4 * 1024 * 1024;
683 net->ipv4.fqdir->low_thresh = 3 * 1024 * 1024;
684 /*
685 * Important NOTE! Fragment queue must be destroyed before MSL expires.
686 * RFC791 is wrong proposing to prolongate timer each fragment arrival
687 * by TTL.
688 */
689 net->ipv4.fqdir->timeout = IP_FRAG_TIME;
690
691 net->ipv4.fqdir->max_dist = 64;
692
693 res = ip4_frags_ns_ctl_register(net);
694 if (res < 0)
695 fqdir_exit(fqdir: net->ipv4.fqdir);
696 return res;
697}
698
699static void __net_exit ipv4_frags_pre_exit_net(struct net *net)
700{
701 fqdir_pre_exit(fqdir: net->ipv4.fqdir);
702}
703
704static void __net_exit ipv4_frags_exit_net(struct net *net)
705{
706 ip4_frags_ns_ctl_unregister(net);
707 fqdir_exit(fqdir: net->ipv4.fqdir);
708}
709
710static struct pernet_operations ip4_frags_ops = {
711 .init = ipv4_frags_init_net,
712 .pre_exit = ipv4_frags_pre_exit_net,
713 .exit = ipv4_frags_exit_net,
714};
715
716
717static u32 ip4_key_hashfn(const void *data, u32 len, u32 seed)
718{
719 return jhash2(k: data,
720 length: sizeof(struct frag_v4_compare_key) / sizeof(u32), initval: seed);
721}
722
723static u32 ip4_obj_hashfn(const void *data, u32 len, u32 seed)
724{
725 const struct inet_frag_queue *fq = data;
726
727 return jhash2(k: (const u32 *)&fq->key.v4,
728 length: sizeof(struct frag_v4_compare_key) / sizeof(u32), initval: seed);
729}
730
731static int ip4_obj_cmpfn(struct rhashtable_compare_arg *arg, const void *ptr)
732{
733 const struct frag_v4_compare_key *key = arg->key;
734 const struct inet_frag_queue *fq = ptr;
735
736 return !!memcmp(p: &fq->key, q: key, size: sizeof(*key));
737}
738
739static const struct rhashtable_params ip4_rhash_params = {
740 .head_offset = offsetof(struct inet_frag_queue, node),
741 .key_offset = offsetof(struct inet_frag_queue, key),
742 .key_len = sizeof(struct frag_v4_compare_key),
743 .hashfn = ip4_key_hashfn,
744 .obj_hashfn = ip4_obj_hashfn,
745 .obj_cmpfn = ip4_obj_cmpfn,
746 .automatic_shrinking = true,
747};
748
749void __init ipfrag_init(void)
750{
751 ip4_frags.constructor = ip4_frag_init;
752 ip4_frags.destructor = ip4_frag_free;
753 ip4_frags.qsize = sizeof(struct ipq);
754 ip4_frags.frag_expire = ip_expire;
755 ip4_frags.frags_cache_name = ip_frag_cache_name;
756 ip4_frags.rhash_params = ip4_rhash_params;
757 if (inet_frags_init(&ip4_frags))
758 panic(fmt: "IP: failed to allocate ip4_frags cache\n");
759 ip4_frags_ctl_register();
760 register_pernet_subsys(&ip4_frags_ops);
761}
762

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