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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 const struct frag_v4_compare_key *key = a;
86 struct net *net = q->fqdir->net;
87 struct inet_peer *p = NULL;
88
89 q->key.v4 = *key;
90 qp->ecn = 0;
91 if (q->fqdir->max_dist) {
92 rcu_read_lock();
93 p = inet_getpeer_v4(net->ipv4.peers, key->saddr, key->vif);
94 if (p && !refcount_inc_not_zero(&p->refcnt))
95 p = NULL;
96 rcu_read_unlock();
97 }
98 qp->peer = p;
99}
100
101static void ip4_frag_free(struct inet_frag_queue *q)
102{
103 struct ipq *qp;
104
105 qp = container_of(q, struct ipq, q);
106 if (qp->peer)
107 inet_putpeer(qp->peer);
108}
109
110
111/* Destruction primitives. */
112
113static void ipq_put(struct ipq *ipq)
114{
115 inet_frag_put(&ipq->q);
116}
117
118/* Kill ipq entry. It is not destroyed immediately,
119 * because caller (and someone more) holds reference count.
120 */
121static void ipq_kill(struct ipq *ipq)
122{
123 inet_frag_kill(&ipq->q);
124}
125
126static bool frag_expire_skip_icmp(u32 user)
127{
128 return user == IP_DEFRAG_AF_PACKET ||
129 ip_defrag_user_in_between(user, IP_DEFRAG_CONNTRACK_IN,
130 __IP_DEFRAG_CONNTRACK_IN_END) ||
131 ip_defrag_user_in_between(user, IP_DEFRAG_CONNTRACK_BRIDGE_IN,
132 __IP_DEFRAG_CONNTRACK_BRIDGE_IN);
133}
134
135/*
136 * Oops, a fragment queue timed out. Kill it and send an ICMP reply.
137 */
138static void ip_expire(struct timer_list *t)
139{
140 enum skb_drop_reason reason = SKB_DROP_REASON_FRAG_REASM_TIMEOUT;
141 struct inet_frag_queue *frag = from_timer(frag, t, timer);
142 const struct iphdr *iph;
143 struct sk_buff *head = NULL;
144 struct net *net;
145 struct ipq *qp;
146
147 qp = container_of(frag, struct ipq, q);
148 net = qp->q.fqdir->net;
149
150 rcu_read_lock();
151
152 /* Paired with WRITE_ONCE() in fqdir_pre_exit(). */
153 if (READ_ONCE(qp->q.fqdir->dead))
154 goto out_rcu_unlock;
155
156 spin_lock(&qp->q.lock);
157
158 if (qp->q.flags & INET_FRAG_COMPLETE)
159 goto out;
160
161 qp->q.flags |= INET_FRAG_DROP;
162 ipq_kill(qp);
163 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
164 __IP_INC_STATS(net, IPSTATS_MIB_REASMTIMEOUT);
165
166 if (!(qp->q.flags & INET_FRAG_FIRST_IN))
167 goto out;
168
169 /* sk_buff::dev and sk_buff::rbnode are unionized. So we
170 * pull the head out of the tree in order to be able to
171 * deal with head->dev.
172 */
173 head = inet_frag_pull_head(&qp->q);
174 if (!head)
175 goto out;
176 head->dev = dev_get_by_index_rcu(net, qp->iif);
177 if (!head->dev)
178 goto out;
179
180
181 /* skb has no dst, perform route lookup again */
182 iph = ip_hdr(head);
183 reason = ip_route_input_noref(head, iph->daddr, iph->saddr,
184 ip4h_dscp(iph), head->dev);
185 if (reason)
186 goto out;
187
188 /* Only an end host needs to send an ICMP
189 * "Fragment Reassembly Timeout" message, per RFC792.
190 */
191 reason = SKB_DROP_REASON_FRAG_REASM_TIMEOUT;
192 if (frag_expire_skip_icmp(qp->q.key.v4.user) &&
193 (skb_rtable(head)->rt_type != RTN_LOCAL))
194 goto out;
195
196 spin_unlock(&qp->q.lock);
197 icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0);
198 goto out_rcu_unlock;
199
200out:
201 spin_unlock(&qp->q.lock);
202out_rcu_unlock:
203 rcu_read_unlock();
204 kfree_skb_reason(head, reason);
205 ipq_put(qp);
206}
207
208/* Find the correct entry in the "incomplete datagrams" queue for
209 * this IP datagram, and create new one, if nothing is found.
210 */
211static struct ipq *ip_find(struct net *net, struct iphdr *iph,
212 u32 user, int vif)
213{
214 struct frag_v4_compare_key key = {
215 .saddr = iph->saddr,
216 .daddr = iph->daddr,
217 .user = user,
218 .vif = vif,
219 .id = iph->id,
220 .protocol = iph->protocol,
221 };
222 struct inet_frag_queue *q;
223
224 q = inet_frag_find(net->ipv4.fqdir, &key);
225 if (!q)
226 return NULL;
227
228 return container_of(q, struct ipq, q);
229}
230
231/* Is the fragment too far ahead to be part of ipq? */
232static int ip_frag_too_far(struct ipq *qp)
233{
234 struct inet_peer *peer = qp->peer;
235 unsigned int max = qp->q.fqdir->max_dist;
236 unsigned int start, end;
237
238 int rc;
239
240 if (!peer || !max)
241 return 0;
242
243 start = qp->rid;
244 end = atomic_inc_return(&peer->rid);
245 qp->rid = end;
246
247 rc = qp->q.fragments_tail && (end - start) > max;
248
249 if (rc)
250 __IP_INC_STATS(qp->q.fqdir->net, IPSTATS_MIB_REASMFAILS);
251
252 return rc;
253}
254
255static int ip_frag_reinit(struct ipq *qp)
256{
257 unsigned int sum_truesize = 0;
258
259 if (!mod_timer(&qp->q.timer, jiffies + qp->q.fqdir->timeout)) {
260 refcount_inc(&qp->q.refcnt);
261 return -ETIMEDOUT;
262 }
263
264 sum_truesize = inet_frag_rbtree_purge(&qp->q.rb_fragments,
265 SKB_DROP_REASON_FRAG_TOO_FAR);
266 sub_frag_mem_limit(qp->q.fqdir, sum_truesize);
267
268 qp->q.flags = 0;
269 qp->q.len = 0;
270 qp->q.meat = 0;
271 qp->q.rb_fragments = RB_ROOT;
272 qp->q.fragments_tail = NULL;
273 qp->q.last_run_head = NULL;
274 qp->iif = 0;
275 qp->ecn = 0;
276
277 return 0;
278}
279
280/* Add new segment to existing queue. */
281static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
282{
283 struct net *net = qp->q.fqdir->net;
284 int ihl, end, flags, offset;
285 struct sk_buff *prev_tail;
286 struct net_device *dev;
287 unsigned int fragsize;
288 int err = -ENOENT;
289 SKB_DR(reason);
290 u8 ecn;
291
292 /* If reassembly is already done, @skb must be a duplicate frag. */
293 if (qp->q.flags & INET_FRAG_COMPLETE) {
294 SKB_DR_SET(reason, DUP_FRAG);
295 goto err;
296 }
297
298 if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) &&
299 unlikely(ip_frag_too_far(qp)) &&
300 unlikely(err = ip_frag_reinit(qp))) {
301 ipq_kill(qp);
302 goto err;
303 }
304
305 ecn = ip4_frag_ecn(ip_hdr(skb)->tos);
306 offset = ntohs(ip_hdr(skb)->frag_off);
307 flags = offset & ~IP_OFFSET;
308 offset &= IP_OFFSET;
309 offset <<= 3; /* offset is in 8-byte chunks */
310 ihl = ip_hdrlen(skb);
311
312 /* Determine the position of this fragment. */
313 end = offset + skb->len - skb_network_offset(skb) - ihl;
314 err = -EINVAL;
315
316 /* Is this the final fragment? */
317 if ((flags & IP_MF) == 0) {
318 /* If we already have some bits beyond end
319 * or have different end, the segment is corrupted.
320 */
321 if (end < qp->q.len ||
322 ((qp->q.flags & INET_FRAG_LAST_IN) && end != qp->q.len))
323 goto discard_qp;
324 qp->q.flags |= INET_FRAG_LAST_IN;
325 qp->q.len = end;
326 } else {
327 if (end&7) {
328 end &= ~7;
329 if (skb->ip_summed != CHECKSUM_UNNECESSARY)
330 skb->ip_summed = CHECKSUM_NONE;
331 }
332 if (end > qp->q.len) {
333 /* Some bits beyond end -> corruption. */
334 if (qp->q.flags & INET_FRAG_LAST_IN)
335 goto discard_qp;
336 qp->q.len = end;
337 }
338 }
339 if (end == offset)
340 goto discard_qp;
341
342 err = -ENOMEM;
343 if (!pskb_pull(skb, skb_network_offset(skb) + ihl))
344 goto discard_qp;
345
346 err = pskb_trim_rcsum(skb, end - offset);
347 if (err)
348 goto discard_qp;
349
350 /* Note : skb->rbnode and skb->dev share the same location. */
351 dev = skb->dev;
352 /* Makes sure compiler wont do silly aliasing games */
353 barrier();
354
355 prev_tail = qp->q.fragments_tail;
356 err = inet_frag_queue_insert(&qp->q, skb, offset, end);
357 if (err)
358 goto insert_error;
359
360 if (dev)
361 qp->iif = dev->ifindex;
362
363 qp->q.stamp = skb->tstamp;
364 qp->q.tstamp_type = skb->tstamp_type;
365 qp->q.meat += skb->len;
366 qp->ecn |= ecn;
367 add_frag_mem_limit(qp->q.fqdir, skb->truesize);
368 if (offset == 0)
369 qp->q.flags |= INET_FRAG_FIRST_IN;
370
371 fragsize = skb->len + ihl;
372
373 if (fragsize > qp->q.max_size)
374 qp->q.max_size = fragsize;
375
376 if (ip_hdr(skb)->frag_off & htons(IP_DF) &&
377 fragsize > qp->max_df_size)
378 qp->max_df_size = fragsize;
379
380 if (qp->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
381 qp->q.meat == qp->q.len) {
382 unsigned long orefdst = skb->_skb_refdst;
383
384 skb->_skb_refdst = 0UL;
385 err = ip_frag_reasm(qp, skb, prev_tail, dev);
386 skb->_skb_refdst = orefdst;
387 if (err)
388 inet_frag_kill(&qp->q);
389 return err;
390 }
391
392 skb_dst_drop(skb);
393 skb_orphan(skb);
394 return -EINPROGRESS;
395
396insert_error:
397 if (err == IPFRAG_DUP) {
398 SKB_DR_SET(reason, DUP_FRAG);
399 err = -EINVAL;
400 goto err;
401 }
402 err = -EINVAL;
403 __IP_INC_STATS(net, IPSTATS_MIB_REASM_OVERLAPS);
404discard_qp:
405 inet_frag_kill(&qp->q);
406 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
407err:
408 kfree_skb_reason(skb, reason);
409 return err;
410}
411
412static bool ip_frag_coalesce_ok(const struct ipq *qp)
413{
414 return qp->q.key.v4.user == IP_DEFRAG_LOCAL_DELIVER;
415}
416
417/* Build a new IP datagram from all its fragments. */
418static int ip_frag_reasm(struct ipq *qp, struct sk_buff *skb,
419 struct sk_buff *prev_tail, struct net_device *dev)
420{
421 struct net *net = qp->q.fqdir->net;
422 struct iphdr *iph;
423 void *reasm_data;
424 int len, err;
425 u8 ecn;
426
427 ipq_kill(qp);
428
429 ecn = ip_frag_ecn_table[qp->ecn];
430 if (unlikely(ecn == 0xff)) {
431 err = -EINVAL;
432 goto out_fail;
433 }
434
435 /* Make the one we just received the head. */
436 reasm_data = inet_frag_reasm_prepare(&qp->q, skb, prev_tail);
437 if (!reasm_data)
438 goto out_nomem;
439
440 len = ip_hdrlen(skb) + qp->q.len;
441 err = -E2BIG;
442 if (len > 65535)
443 goto out_oversize;
444
445 inet_frag_reasm_finish(&qp->q, skb, reasm_data,
446 ip_frag_coalesce_ok(qp));
447
448 skb->dev = dev;
449 IPCB(skb)->frag_max_size = max(qp->max_df_size, qp->q.max_size);
450
451 iph = ip_hdr(skb);
452 iph->tot_len = htons(len);
453 iph->tos |= ecn;
454
455 /* When we set IP_DF on a refragmented skb we must also force a
456 * call to ip_fragment to avoid forwarding a DF-skb of size s while
457 * original sender only sent fragments of size f (where f < s).
458 *
459 * We only set DF/IPSKB_FRAG_PMTU if such DF fragment was the largest
460 * frag seen to avoid sending tiny DF-fragments in case skb was built
461 * from one very small df-fragment and one large non-df frag.
462 */
463 if (qp->max_df_size == qp->q.max_size) {
464 IPCB(skb)->flags |= IPSKB_FRAG_PMTU;
465 iph->frag_off = htons(IP_DF);
466 } else {
467 iph->frag_off = 0;
468 }
469
470 ip_send_check(iph);
471
472 __IP_INC_STATS(net, IPSTATS_MIB_REASMOKS);
473 qp->q.rb_fragments = RB_ROOT;
474 qp->q.fragments_tail = NULL;
475 qp->q.last_run_head = NULL;
476 return 0;
477
478out_nomem:
479 net_dbg_ratelimited("queue_glue: no memory for gluing queue %p\n", qp);
480 err = -ENOMEM;
481 goto out_fail;
482out_oversize:
483 net_info_ratelimited("Oversized IP packet from %pI4\n", &qp->q.key.v4.saddr);
484out_fail:
485 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
486 return err;
487}
488
489/* Process an incoming IP datagram fragment. */
490int ip_defrag(struct net *net, struct sk_buff *skb, u32 user)
491{
492 struct net_device *dev = skb->dev ? : skb_dst(skb)->dev;
493 int vif = l3mdev_master_ifindex_rcu(dev);
494 struct ipq *qp;
495
496 __IP_INC_STATS(net, IPSTATS_MIB_REASMREQDS);
497
498 /* Lookup (or create) queue header */
499 qp = ip_find(net, ip_hdr(skb), user, vif);
500 if (qp) {
501 int ret;
502
503 spin_lock(&qp->q.lock);
504
505 ret = ip_frag_queue(qp, skb);
506
507 spin_unlock(&qp->q.lock);
508 ipq_put(qp);
509 return ret;
510 }
511
512 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
513 kfree_skb(skb);
514 return -ENOMEM;
515}
516EXPORT_SYMBOL(ip_defrag);
517
518struct sk_buff *ip_check_defrag(struct net *net, struct sk_buff *skb, u32 user)
519{
520 struct iphdr iph;
521 int netoff;
522 u32 len;
523
524 if (skb->protocol != htons(ETH_P_IP))
525 return skb;
526
527 netoff = skb_network_offset(skb);
528
529 if (skb_copy_bits(skb, netoff, &iph, sizeof(iph)) < 0)
530 return skb;
531
532 if (iph.ihl < 5 || iph.version != 4)
533 return skb;
534
535 len = ntohs(iph.tot_len);
536 if (skb->len < netoff + len || len < (iph.ihl * 4))
537 return skb;
538
539 if (ip_is_fragment(&iph)) {
540 skb = skb_share_check(skb, GFP_ATOMIC);
541 if (skb) {
542 if (!pskb_may_pull(skb, netoff + iph.ihl * 4)) {
543 kfree_skb(skb);
544 return NULL;
545 }
546 if (pskb_trim_rcsum(skb, netoff + len)) {
547 kfree_skb(skb);
548 return NULL;
549 }
550 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
551 if (ip_defrag(net, skb, user))
552 return NULL;
553 skb_clear_hash(skb);
554 }
555 }
556 return skb;
557}
558EXPORT_SYMBOL(ip_check_defrag);
559
560#ifdef CONFIG_SYSCTL
561static int dist_min;
562
563static struct ctl_table ip4_frags_ns_ctl_table[] = {
564 {
565 .procname = "ipfrag_high_thresh",
566 .maxlen = sizeof(unsigned long),
567 .mode = 0644,
568 .proc_handler = proc_doulongvec_minmax,
569 },
570 {
571 .procname = "ipfrag_low_thresh",
572 .maxlen = sizeof(unsigned long),
573 .mode = 0644,
574 .proc_handler = proc_doulongvec_minmax,
575 },
576 {
577 .procname = "ipfrag_time",
578 .maxlen = sizeof(int),
579 .mode = 0644,
580 .proc_handler = proc_dointvec_jiffies,
581 },
582 {
583 .procname = "ipfrag_max_dist",
584 .maxlen = sizeof(int),
585 .mode = 0644,
586 .proc_handler = proc_dointvec_minmax,
587 .extra1 = &dist_min,
588 },
589};
590
591/* secret interval has been deprecated */
592static int ip4_frags_secret_interval_unused;
593static struct ctl_table ip4_frags_ctl_table[] = {
594 {
595 .procname = "ipfrag_secret_interval",
596 .data = &ip4_frags_secret_interval_unused,
597 .maxlen = sizeof(int),
598 .mode = 0644,
599 .proc_handler = proc_dointvec_jiffies,
600 },
601};
602
603static int __net_init ip4_frags_ns_ctl_register(struct net *net)
604{
605 struct ctl_table *table;
606 struct ctl_table_header *hdr;
607
608 table = ip4_frags_ns_ctl_table;
609 if (!net_eq(net, &init_net)) {
610 table = kmemdup(table, sizeof(ip4_frags_ns_ctl_table), GFP_KERNEL);
611 if (!table)
612 goto err_alloc;
613
614 }
615 table[0].data = &net->ipv4.fqdir->high_thresh;
616 table[0].extra1 = &net->ipv4.fqdir->low_thresh;
617 table[1].data = &net->ipv4.fqdir->low_thresh;
618 table[1].extra2 = &net->ipv4.fqdir->high_thresh;
619 table[2].data = &net->ipv4.fqdir->timeout;
620 table[3].data = &net->ipv4.fqdir->max_dist;
621
622 hdr = register_net_sysctl_sz(net, "net/ipv4", table,
623 ARRAY_SIZE(ip4_frags_ns_ctl_table));
624 if (!hdr)
625 goto err_reg;
626
627 net->ipv4.frags_hdr = hdr;
628 return 0;
629
630err_reg:
631 if (!net_eq(net, &init_net))
632 kfree(table);
633err_alloc:
634 return -ENOMEM;
635}
636
637static void __net_exit ip4_frags_ns_ctl_unregister(struct net *net)
638{
639 const struct ctl_table *table;
640
641 table = net->ipv4.frags_hdr->ctl_table_arg;
642 unregister_net_sysctl_table(net->ipv4.frags_hdr);
643 kfree(table);
644}
645
646static void __init ip4_frags_ctl_register(void)
647{
648 register_net_sysctl(&init_net, "net/ipv4", ip4_frags_ctl_table);
649}
650#else
651static int ip4_frags_ns_ctl_register(struct net *net)
652{
653 return 0;
654}
655
656static void ip4_frags_ns_ctl_unregister(struct net *net)
657{
658}
659
660static void __init ip4_frags_ctl_register(void)
661{
662}
663#endif
664
665static int __net_init ipv4_frags_init_net(struct net *net)
666{
667 int res;
668
669 res = fqdir_init(&net->ipv4.fqdir, &ip4_frags, net);
670 if (res < 0)
671 return res;
672 /* Fragment cache limits.
673 *
674 * The fragment memory accounting code, (tries to) account for
675 * the real memory usage, by measuring both the size of frag
676 * queue struct (inet_frag_queue (ipv4:ipq/ipv6:frag_queue))
677 * and the SKB's truesize.
678 *
679 * A 64K fragment consumes 129736 bytes (44*2944)+200
680 * (1500 truesize == 2944, sizeof(struct ipq) == 200)
681 *
682 * We will commit 4MB at one time. Should we cross that limit
683 * we will prune down to 3MB, making room for approx 8 big 64K
684 * fragments 8x128k.
685 */
686 net->ipv4.fqdir->high_thresh = 4 * 1024 * 1024;
687 net->ipv4.fqdir->low_thresh = 3 * 1024 * 1024;
688 /*
689 * Important NOTE! Fragment queue must be destroyed before MSL expires.
690 * RFC791 is wrong proposing to prolongate timer each fragment arrival
691 * by TTL.
692 */
693 net->ipv4.fqdir->timeout = IP_FRAG_TIME;
694
695 net->ipv4.fqdir->max_dist = 64;
696
697 res = ip4_frags_ns_ctl_register(net);
698 if (res < 0)
699 fqdir_exit(net->ipv4.fqdir);
700 return res;
701}
702
703static void __net_exit ipv4_frags_pre_exit_net(struct net *net)
704{
705 fqdir_pre_exit(net->ipv4.fqdir);
706}
707
708static void __net_exit ipv4_frags_exit_net(struct net *net)
709{
710 ip4_frags_ns_ctl_unregister(net);
711 fqdir_exit(net->ipv4.fqdir);
712}
713
714static struct pernet_operations ip4_frags_ops = {
715 .init = ipv4_frags_init_net,
716 .pre_exit = ipv4_frags_pre_exit_net,
717 .exit = ipv4_frags_exit_net,
718};
719
720
721static u32 ip4_key_hashfn(const void *data, u32 len, u32 seed)
722{
723 return jhash2(data,
724 sizeof(struct frag_v4_compare_key) / sizeof(u32), seed);
725}
726
727static u32 ip4_obj_hashfn(const void *data, u32 len, u32 seed)
728{
729 const struct inet_frag_queue *fq = data;
730
731 return jhash2((const u32 *)&fq->key.v4,
732 sizeof(struct frag_v4_compare_key) / sizeof(u32), seed);
733}
734
735static int ip4_obj_cmpfn(struct rhashtable_compare_arg *arg, const void *ptr)
736{
737 const struct frag_v4_compare_key *key = arg->key;
738 const struct inet_frag_queue *fq = ptr;
739
740 return !!memcmp(&fq->key, key, sizeof(*key));
741}
742
743static const struct rhashtable_params ip4_rhash_params = {
744 .head_offset = offsetof(struct inet_frag_queue, node),
745 .key_offset = offsetof(struct inet_frag_queue, key),
746 .key_len = sizeof(struct frag_v4_compare_key),
747 .hashfn = ip4_key_hashfn,
748 .obj_hashfn = ip4_obj_hashfn,
749 .obj_cmpfn = ip4_obj_cmpfn,
750 .automatic_shrinking = true,
751};
752
753void __init ipfrag_init(void)
754{
755 ip4_frags.constructor = ip4_frag_init;
756 ip4_frags.destructor = ip4_frag_free;
757 ip4_frags.qsize = sizeof(struct ipq);
758 ip4_frags.frag_expire = ip_expire;
759 ip4_frags.frags_cache_name = ip_frag_cache_name;
760 ip4_frags.rhash_params = ip4_rhash_params;
761 if (inet_frags_init(&ip4_frags))
762 panic("IP: failed to allocate ip4_frags cache\n");
763 ip4_frags_ctl_register();
764 register_pernet_subsys(&ip4_frags_ops);
765}
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(net->ipv4.peers, key->saddr, key->vif, 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(qp->peer);
103}
104
105
106/* Destruction primitives. */
107
108static void ipq_put(struct ipq *ipq)
109{
110 inet_frag_put(&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(&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, IP_DEFRAG_CONNTRACK_IN,
125 __IP_DEFRAG_CONNTRACK_IN_END) ||
126 ip_defrag_user_in_between(user, IP_DEFRAG_CONNTRACK_BRIDGE_IN,
127 __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(&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(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(&qp->q);
169 if (!head)
170 goto out;
171 head->dev = dev_get_by_index_rcu(net, qp->iif);
172 if (!head->dev)
173 goto out;
174
175
176 /* skb has no dst, perform route lookup again */
177 iph = ip_hdr(head);
178 err = ip_route_input_noref(head, iph->daddr, iph->saddr,
179 iph->tos, 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(qp->q.key.v4.user) &&
187 (skb_rtable(head)->rt_type != RTN_LOCAL))
188 goto out;
189
190 spin_unlock(&qp->q.lock);
191 icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0);
192 goto out_rcu_unlock;
193
194out:
195 spin_unlock(&qp->q.lock);
196out_rcu_unlock:
197 rcu_read_unlock();
198 kfree_skb_reason(head, SKB_DROP_REASON_FRAG_REASM_TIMEOUT);
199 ipq_put(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(net->ipv4.fqdir, &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(&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(&qp->q.timer, jiffies + qp->q.fqdir->timeout)) {
254 refcount_inc(&qp->q.refcnt);
255 return -ETIMEDOUT;
256 }
257
258 sum_truesize = inet_frag_rbtree_purge(&qp->q.rb_fragments,
259 SKB_DROP_REASON_FRAG_TOO_FAR);
260 sub_frag_mem_limit(qp->q.fqdir, 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(qp);
296 goto err;
297 }
298
299 ecn = ip4_frag_ecn(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, skb_network_offset(skb) + ihl))
338 goto discard_qp;
339
340 err = pskb_trim_rcsum(skb, 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(&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(qp->q.fqdir, 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(&qp->q);
383 return err;
384 }
385
386 skb_dst_drop(skb);
387 return -EINPROGRESS;
388
389insert_error:
390 if (err == IPFRAG_DUP) {
391 SKB_DR_SET(reason, DUP_FRAG);
392 err = -EINVAL;
393 goto err;
394 }
395 err = -EINVAL;
396 __IP_INC_STATS(net, IPSTATS_MIB_REASM_OVERLAPS);
397discard_qp:
398 inet_frag_kill(&qp->q);
399 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
400err:
401 kfree_skb_reason(skb, reason);
402 return err;
403}
404
405static bool ip_frag_coalesce_ok(const struct ipq *qp)
406{
407 return qp->q.key.v4.user == IP_DEFRAG_LOCAL_DELIVER;
408}
409
410/* Build a new IP datagram from all its fragments. */
411static int ip_frag_reasm(struct ipq *qp, struct sk_buff *skb,
412 struct sk_buff *prev_tail, struct net_device *dev)
413{
414 struct net *net = qp->q.fqdir->net;
415 struct iphdr *iph;
416 void *reasm_data;
417 int len, err;
418 u8 ecn;
419
420 ipq_kill(qp);
421
422 ecn = ip_frag_ecn_table[qp->ecn];
423 if (unlikely(ecn == 0xff)) {
424 err = -EINVAL;
425 goto out_fail;
426 }
427
428 /* Make the one we just received the head. */
429 reasm_data = inet_frag_reasm_prepare(&qp->q, skb, prev_tail);
430 if (!reasm_data)
431 goto out_nomem;
432
433 len = ip_hdrlen(skb) + qp->q.len;
434 err = -E2BIG;
435 if (len > 65535)
436 goto out_oversize;
437
438 inet_frag_reasm_finish(&qp->q, skb, reasm_data,
439 ip_frag_coalesce_ok(qp));
440
441 skb->dev = dev;
442 IPCB(skb)->frag_max_size = max(qp->max_df_size, qp->q.max_size);
443
444 iph = ip_hdr(skb);
445 iph->tot_len = htons(len);
446 iph->tos |= ecn;
447
448 /* When we set IP_DF on a refragmented skb we must also force a
449 * call to ip_fragment to avoid forwarding a DF-skb of size s while
450 * original sender only sent fragments of size f (where f < s).
451 *
452 * We only set DF/IPSKB_FRAG_PMTU if such DF fragment was the largest
453 * frag seen to avoid sending tiny DF-fragments in case skb was built
454 * from one very small df-fragment and one large non-df frag.
455 */
456 if (qp->max_df_size == qp->q.max_size) {
457 IPCB(skb)->flags |= IPSKB_FRAG_PMTU;
458 iph->frag_off = htons(IP_DF);
459 } else {
460 iph->frag_off = 0;
461 }
462
463 ip_send_check(iph);
464
465 __IP_INC_STATS(net, IPSTATS_MIB_REASMOKS);
466 qp->q.rb_fragments = RB_ROOT;
467 qp->q.fragments_tail = NULL;
468 qp->q.last_run_head = NULL;
469 return 0;
470
471out_nomem:
472 net_dbg_ratelimited("queue_glue: no memory for gluing queue %p\n", qp);
473 err = -ENOMEM;
474 goto out_fail;
475out_oversize:
476 net_info_ratelimited("Oversized IP packet from %pI4\n", &qp->q.key.v4.saddr);
477out_fail:
478 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
479 return err;
480}
481
482/* Process an incoming IP datagram fragment. */
483int ip_defrag(struct net *net, struct sk_buff *skb, u32 user)
484{
485 struct net_device *dev = skb->dev ? : skb_dst(skb)->dev;
486 int vif = l3mdev_master_ifindex_rcu(dev);
487 struct ipq *qp;
488
489 __IP_INC_STATS(net, IPSTATS_MIB_REASMREQDS);
490 skb_orphan(skb);
491
492 /* Lookup (or create) queue header */
493 qp = ip_find(net, ip_hdr(skb), user, vif);
494 if (qp) {
495 int ret;
496
497 spin_lock(&qp->q.lock);
498
499 ret = ip_frag_queue(qp, skb);
500
501 spin_unlock(&qp->q.lock);
502 ipq_put(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, netoff, &iph, 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)) {
534 skb = skb_share_check(skb, GFP_ATOMIC);
535 if (skb) {
536 if (!pskb_may_pull(skb, netoff + iph.ihl * 4)) {
537 kfree_skb(skb);
538 return NULL;
539 }
540 if (pskb_trim_rcsum(skb, 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(net, &init_net)) {
606 table = kmemdup(table, 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(net, "net/ipv4", table);
619 if (!hdr)
620 goto err_reg;
621
622 net->ipv4.frags_hdr = hdr;
623 return 0;
624
625err_reg:
626 if (!net_eq(net, &init_net))
627 kfree(table);
628err_alloc:
629 return -ENOMEM;
630}
631
632static void __net_exit ip4_frags_ns_ctl_unregister(struct net *net)
633{
634 struct ctl_table *table;
635
636 table = net->ipv4.frags_hdr->ctl_table_arg;
637 unregister_net_sysctl_table(net->ipv4.frags_hdr);
638 kfree(table);
639}
640
641static void __init ip4_frags_ctl_register(void)
642{
643 register_net_sysctl(&init_net, "net/ipv4", ip4_frags_ctl_table);
644}
645#else
646static int ip4_frags_ns_ctl_register(struct net *net)
647{
648 return 0;
649}
650
651static void ip4_frags_ns_ctl_unregister(struct net *net)
652{
653}
654
655static void __init ip4_frags_ctl_register(void)
656{
657}
658#endif
659
660static int __net_init ipv4_frags_init_net(struct net *net)
661{
662 int res;
663
664 res = fqdir_init(&net->ipv4.fqdir, &ip4_frags, net);
665 if (res < 0)
666 return res;
667 /* Fragment cache limits.
668 *
669 * The fragment memory accounting code, (tries to) account for
670 * the real memory usage, by measuring both the size of frag
671 * queue struct (inet_frag_queue (ipv4:ipq/ipv6:frag_queue))
672 * and the SKB's truesize.
673 *
674 * A 64K fragment consumes 129736 bytes (44*2944)+200
675 * (1500 truesize == 2944, sizeof(struct ipq) == 200)
676 *
677 * We will commit 4MB at one time. Should we cross that limit
678 * we will prune down to 3MB, making room for approx 8 big 64K
679 * fragments 8x128k.
680 */
681 net->ipv4.fqdir->high_thresh = 4 * 1024 * 1024;
682 net->ipv4.fqdir->low_thresh = 3 * 1024 * 1024;
683 /*
684 * Important NOTE! Fragment queue must be destroyed before MSL expires.
685 * RFC791 is wrong proposing to prolongate timer each fragment arrival
686 * by TTL.
687 */
688 net->ipv4.fqdir->timeout = IP_FRAG_TIME;
689
690 net->ipv4.fqdir->max_dist = 64;
691
692 res = ip4_frags_ns_ctl_register(net);
693 if (res < 0)
694 fqdir_exit(net->ipv4.fqdir);
695 return res;
696}
697
698static void __net_exit ipv4_frags_pre_exit_net(struct net *net)
699{
700 fqdir_pre_exit(net->ipv4.fqdir);
701}
702
703static void __net_exit ipv4_frags_exit_net(struct net *net)
704{
705 ip4_frags_ns_ctl_unregister(net);
706 fqdir_exit(net->ipv4.fqdir);
707}
708
709static struct pernet_operations ip4_frags_ops = {
710 .init = ipv4_frags_init_net,
711 .pre_exit = ipv4_frags_pre_exit_net,
712 .exit = ipv4_frags_exit_net,
713};
714
715
716static u32 ip4_key_hashfn(const void *data, u32 len, u32 seed)
717{
718 return jhash2(data,
719 sizeof(struct frag_v4_compare_key) / sizeof(u32), seed);
720}
721
722static u32 ip4_obj_hashfn(const void *data, u32 len, u32 seed)
723{
724 const struct inet_frag_queue *fq = data;
725
726 return jhash2((const u32 *)&fq->key.v4,
727 sizeof(struct frag_v4_compare_key) / sizeof(u32), seed);
728}
729
730static int ip4_obj_cmpfn(struct rhashtable_compare_arg *arg, const void *ptr)
731{
732 const struct frag_v4_compare_key *key = arg->key;
733 const struct inet_frag_queue *fq = ptr;
734
735 return !!memcmp(&fq->key, key, sizeof(*key));
736}
737
738static const struct rhashtable_params ip4_rhash_params = {
739 .head_offset = offsetof(struct inet_frag_queue, node),
740 .key_offset = offsetof(struct inet_frag_queue, key),
741 .key_len = sizeof(struct frag_v4_compare_key),
742 .hashfn = ip4_key_hashfn,
743 .obj_hashfn = ip4_obj_hashfn,
744 .obj_cmpfn = ip4_obj_cmpfn,
745 .automatic_shrinking = true,
746};
747
748void __init ipfrag_init(void)
749{
750 ip4_frags.constructor = ip4_frag_init;
751 ip4_frags.destructor = ip4_frag_free;
752 ip4_frags.qsize = sizeof(struct ipq);
753 ip4_frags.frag_expire = ip_expire;
754 ip4_frags.frags_cache_name = ip_frag_cache_name;
755 ip4_frags.rhash_params = ip4_rhash_params;
756 if (inet_frags_init(&ip4_frags))
757 panic("IP: failed to allocate ip4_frags cache\n");
758 ip4_frags_ctl_register();
759 register_pernet_subsys(&ip4_frags_ops);
760}