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 */
58 static const char ip_frag_cache_name[] = "ip4-frags";
59
60 /* Describe an entry in the "incomplete datagrams" queue. */
61 struct 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
ip4_frag_ecn(u8 tos)71 static u8 ip4_frag_ecn(u8 tos)
72 {
73 return 1 << (tos & INET_ECN_MASK);
74 }
75
76 static struct inet_frags ip4_frags;
77
78 static 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
ip4_frag_init(struct inet_frag_queue * q,const void * a)83 static 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(net->ipv4.peers, key->saddr, key->vif);
95 if (p && !refcount_inc_not_zero(&p->refcnt))
96 p = NULL;
97 rcu_read_unlock();
98 }
99 qp->peer = p;
100 }
101
ip4_frag_free(struct inet_frag_queue * q)102 static 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(qp->peer);
109 }
110
frag_expire_skip_icmp(u32 user)111 static bool frag_expire_skip_icmp(u32 user)
112 {
113 return user == IP_DEFRAG_AF_PACKET ||
114 ip_defrag_user_in_between(user, IP_DEFRAG_CONNTRACK_IN,
115 __IP_DEFRAG_CONNTRACK_IN_END) ||
116 ip_defrag_user_in_between(user, IP_DEFRAG_CONNTRACK_BRIDGE_IN,
117 __IP_DEFRAG_CONNTRACK_BRIDGE_IN);
118 }
119
120 /*
121 * Oops, a fragment queue timed out. Kill it and send an ICMP reply.
122 */
ip_expire(struct timer_list * t)123 static 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
138 /* Paired with WRITE_ONCE() in fqdir_pre_exit(). */
139 if (READ_ONCE(qp->q.fqdir->dead))
140 goto out_rcu_unlock;
141
142 spin_lock(&qp->q.lock);
143
144 if (qp->q.flags & INET_FRAG_COMPLETE)
145 goto out;
146
147 qp->q.flags |= INET_FRAG_DROP;
148 inet_frag_kill(&qp->q, &refs);
149 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
150 __IP_INC_STATS(net, IPSTATS_MIB_REASMTIMEOUT);
151
152 if (!(qp->q.flags & INET_FRAG_FIRST_IN))
153 goto out;
154
155 /* sk_buff::dev and sk_buff::rbnode are unionized. So we
156 * pull the head out of the tree in order to be able to
157 * deal with head->dev.
158 */
159 head = inet_frag_pull_head(&qp->q);
160 if (!head)
161 goto out;
162 head->dev = dev_get_by_index_rcu(net, qp->iif);
163 if (!head->dev)
164 goto out;
165
166
167 /* skb has no dst, perform route lookup again */
168 iph = ip_hdr(head);
169 reason = ip_route_input_noref(head, iph->daddr, iph->saddr,
170 ip4h_dscp(iph), head->dev);
171 if (reason)
172 goto out;
173
174 /* Only an end host needs to send an ICMP
175 * "Fragment Reassembly Timeout" message, per RFC792.
176 */
177 reason = SKB_DROP_REASON_FRAG_REASM_TIMEOUT;
178 if (frag_expire_skip_icmp(qp->q.key.v4.user) &&
179 (skb_rtable(head)->rt_type != RTN_LOCAL))
180 goto out;
181
182 spin_unlock(&qp->q.lock);
183 icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0);
184 goto out_rcu_unlock;
185
186 out:
187 spin_unlock(&qp->q.lock);
188 out_rcu_unlock:
189 rcu_read_unlock();
190 kfree_skb_reason(head, reason);
191 inet_frag_putn(&qp->q, refs);
192 }
193
194 /* Find the correct entry in the "incomplete datagrams" queue for
195 * this IP datagram, and create new one, if nothing is found.
196 */
ip_find(struct net * net,struct iphdr * iph,u32 user,int vif)197 static struct ipq *ip_find(struct net *net, struct iphdr *iph,
198 u32 user, int vif)
199 {
200 struct frag_v4_compare_key key = {
201 .saddr = iph->saddr,
202 .daddr = iph->daddr,
203 .user = user,
204 .vif = vif,
205 .id = iph->id,
206 .protocol = iph->protocol,
207 };
208 struct inet_frag_queue *q;
209
210 q = inet_frag_find(net->ipv4.fqdir, &key);
211 if (!q)
212 return NULL;
213
214 return container_of(q, struct ipq, q);
215 }
216
217 /* Is the fragment too far ahead to be part of ipq? */
ip_frag_too_far(struct ipq * qp)218 static int ip_frag_too_far(struct ipq *qp)
219 {
220 struct inet_peer *peer = qp->peer;
221 unsigned int max = qp->q.fqdir->max_dist;
222 unsigned int start, end;
223
224 int rc;
225
226 if (!peer || !max)
227 return 0;
228
229 start = qp->rid;
230 end = atomic_inc_return(&peer->rid);
231 qp->rid = end;
232
233 rc = qp->q.fragments_tail && (end - start) > max;
234
235 if (rc)
236 __IP_INC_STATS(qp->q.fqdir->net, IPSTATS_MIB_REASMFAILS);
237
238 return rc;
239 }
240
ip_frag_reinit(struct ipq * qp)241 static int ip_frag_reinit(struct ipq *qp)
242 {
243 unsigned int sum_truesize = 0;
244
245 if (!mod_timer(&qp->q.timer, jiffies + qp->q.fqdir->timeout)) {
246 refcount_inc(&qp->q.refcnt);
247 return -ETIMEDOUT;
248 }
249
250 sum_truesize = inet_frag_rbtree_purge(&qp->q.rb_fragments,
251 SKB_DROP_REASON_FRAG_TOO_FAR);
252 sub_frag_mem_limit(qp->q.fqdir, sum_truesize);
253
254 qp->q.flags = 0;
255 qp->q.len = 0;
256 qp->q.meat = 0;
257 qp->q.rb_fragments = RB_ROOT;
258 qp->q.fragments_tail = NULL;
259 qp->q.last_run_head = NULL;
260 qp->iif = 0;
261 qp->ecn = 0;
262
263 return 0;
264 }
265
266 /* Add new segment to existing queue. */
ip_frag_queue(struct ipq * qp,struct sk_buff * skb,int * refs)267 static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb, int *refs)
268 {
269 struct net *net = qp->q.fqdir->net;
270 int ihl, end, flags, offset;
271 struct sk_buff *prev_tail;
272 struct net_device *dev;
273 unsigned int fragsize;
274 int err = -ENOENT;
275 SKB_DR(reason);
276 u8 ecn;
277
278 /* If reassembly is already done, @skb must be a duplicate frag. */
279 if (qp->q.flags & INET_FRAG_COMPLETE) {
280 SKB_DR_SET(reason, DUP_FRAG);
281 goto err;
282 }
283
284 if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) &&
285 unlikely(ip_frag_too_far(qp)) &&
286 unlikely(err = ip_frag_reinit(qp))) {
287 inet_frag_kill(&qp->q, refs);
288 goto err;
289 }
290
291 ecn = ip4_frag_ecn(ip_hdr(skb)->tos);
292 offset = ntohs(ip_hdr(skb)->frag_off);
293 flags = offset & ~IP_OFFSET;
294 offset &= IP_OFFSET;
295 offset <<= 3; /* offset is in 8-byte chunks */
296 ihl = ip_hdrlen(skb);
297
298 /* Determine the position of this fragment. */
299 end = offset + skb->len - skb_network_offset(skb) - ihl;
300 err = -EINVAL;
301
302 /* Is this the final fragment? */
303 if ((flags & IP_MF) == 0) {
304 /* If we already have some bits beyond end
305 * or have different end, the segment is corrupted.
306 */
307 if (end < qp->q.len ||
308 ((qp->q.flags & INET_FRAG_LAST_IN) && end != qp->q.len))
309 goto discard_qp;
310 qp->q.flags |= INET_FRAG_LAST_IN;
311 qp->q.len = end;
312 } else {
313 if (end&7) {
314 end &= ~7;
315 if (skb->ip_summed != CHECKSUM_UNNECESSARY)
316 skb->ip_summed = CHECKSUM_NONE;
317 }
318 if (end > qp->q.len) {
319 /* Some bits beyond end -> corruption. */
320 if (qp->q.flags & INET_FRAG_LAST_IN)
321 goto discard_qp;
322 qp->q.len = end;
323 }
324 }
325 if (end == offset)
326 goto discard_qp;
327
328 err = -ENOMEM;
329 if (!pskb_pull(skb, skb_network_offset(skb) + ihl))
330 goto discard_qp;
331
332 err = pskb_trim_rcsum(skb, end - offset);
333 if (err)
334 goto discard_qp;
335
336 /* Note : skb->rbnode and skb->dev share the same location. */
337 dev = skb->dev;
338 /* Makes sure compiler wont do silly aliasing games */
339 barrier();
340
341 prev_tail = qp->q.fragments_tail;
342 err = inet_frag_queue_insert(&qp->q, skb, offset, end);
343 if (err)
344 goto insert_error;
345
346 if (dev)
347 qp->iif = dev->ifindex;
348
349 qp->q.stamp = skb->tstamp;
350 qp->q.tstamp_type = skb->tstamp_type;
351 qp->q.meat += skb->len;
352 qp->ecn |= ecn;
353 add_frag_mem_limit(qp->q.fqdir, skb->truesize);
354 if (offset == 0)
355 qp->q.flags |= INET_FRAG_FIRST_IN;
356
357 fragsize = skb->len + ihl;
358
359 if (fragsize > qp->q.max_size)
360 qp->q.max_size = fragsize;
361
362 if (ip_hdr(skb)->frag_off & htons(IP_DF) &&
363 fragsize > qp->max_df_size)
364 qp->max_df_size = fragsize;
365
366 if (qp->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
367 qp->q.meat == qp->q.len) {
368 unsigned long orefdst = skb->_skb_refdst;
369
370 skb->_skb_refdst = 0UL;
371 err = ip_frag_reasm(qp, skb, prev_tail, dev, refs);
372 skb->_skb_refdst = orefdst;
373 if (err)
374 inet_frag_kill(&qp->q, refs);
375 return err;
376 }
377
378 skb_dst_drop(skb);
379 skb_orphan(skb);
380 return -EINPROGRESS;
381
382 insert_error:
383 if (err == IPFRAG_DUP) {
384 SKB_DR_SET(reason, DUP_FRAG);
385 err = -EINVAL;
386 goto err;
387 }
388 err = -EINVAL;
389 __IP_INC_STATS(net, IPSTATS_MIB_REASM_OVERLAPS);
390 discard_qp:
391 inet_frag_kill(&qp->q, refs);
392 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
393 err:
394 kfree_skb_reason(skb, reason);
395 return err;
396 }
397
ip_frag_coalesce_ok(const struct ipq * qp)398 static bool ip_frag_coalesce_ok(const struct ipq *qp)
399 {
400 return qp->q.key.v4.user == IP_DEFRAG_LOCAL_DELIVER;
401 }
402
403 /* Build a new IP datagram from all its fragments. */
ip_frag_reasm(struct ipq * qp,struct sk_buff * skb,struct sk_buff * prev_tail,struct net_device * dev,int * refs)404 static int ip_frag_reasm(struct ipq *qp, struct sk_buff *skb,
405 struct sk_buff *prev_tail, struct net_device *dev,
406 int *refs)
407 {
408 struct net *net = qp->q.fqdir->net;
409 struct iphdr *iph;
410 void *reasm_data;
411 int len, err;
412 u8 ecn;
413
414 inet_frag_kill(&qp->q, refs);
415
416 ecn = ip_frag_ecn_table[qp->ecn];
417 if (unlikely(ecn == 0xff)) {
418 err = -EINVAL;
419 goto out_fail;
420 }
421
422 /* Make the one we just received the head. */
423 reasm_data = inet_frag_reasm_prepare(&qp->q, skb, prev_tail);
424 if (!reasm_data)
425 goto out_nomem;
426
427 len = ip_hdrlen(skb) + qp->q.len;
428 err = -E2BIG;
429 if (len > 65535)
430 goto out_oversize;
431
432 inet_frag_reasm_finish(&qp->q, skb, reasm_data,
433 ip_frag_coalesce_ok(qp));
434
435 skb->dev = dev;
436 IPCB(skb)->frag_max_size = max(qp->max_df_size, qp->q.max_size);
437
438 iph = ip_hdr(skb);
439 iph->tot_len = htons(len);
440 iph->tos |= ecn;
441
442 /* When we set IP_DF on a refragmented skb we must also force a
443 * call to ip_fragment to avoid forwarding a DF-skb of size s while
444 * original sender only sent fragments of size f (where f < s).
445 *
446 * We only set DF/IPSKB_FRAG_PMTU if such DF fragment was the largest
447 * frag seen to avoid sending tiny DF-fragments in case skb was built
448 * from one very small df-fragment and one large non-df frag.
449 */
450 if (qp->max_df_size == qp->q.max_size) {
451 IPCB(skb)->flags |= IPSKB_FRAG_PMTU;
452 iph->frag_off = htons(IP_DF);
453 } else {
454 iph->frag_off = 0;
455 }
456
457 ip_send_check(iph);
458
459 __IP_INC_STATS(net, IPSTATS_MIB_REASMOKS);
460 qp->q.rb_fragments = RB_ROOT;
461 qp->q.fragments_tail = NULL;
462 qp->q.last_run_head = NULL;
463 return 0;
464
465 out_nomem:
466 net_dbg_ratelimited("queue_glue: no memory for gluing queue %p\n", qp);
467 err = -ENOMEM;
468 goto out_fail;
469 out_oversize:
470 net_info_ratelimited("Oversized IP packet from %pI4\n", &qp->q.key.v4.saddr);
471 out_fail:
472 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
473 return err;
474 }
475
476 /* Process an incoming IP datagram fragment. */
ip_defrag(struct net * net,struct sk_buff * skb,u32 user)477 int ip_defrag(struct net *net, struct sk_buff *skb, u32 user)
478 {
479 struct net_device *dev = skb->dev ? : skb_dst(skb)->dev;
480 int vif = l3mdev_master_ifindex_rcu(dev);
481 struct ipq *qp;
482
483 __IP_INC_STATS(net, IPSTATS_MIB_REASMREQDS);
484
485 /* Lookup (or create) queue header */
486 rcu_read_lock();
487 qp = ip_find(net, ip_hdr(skb), user, vif);
488 if (qp) {
489 int ret, refs = 0;
490
491 spin_lock(&qp->q.lock);
492
493 ret = ip_frag_queue(qp, skb, &refs);
494
495 spin_unlock(&qp->q.lock);
496 rcu_read_unlock();
497 inet_frag_putn(&qp->q, refs);
498 return ret;
499 }
500 rcu_read_unlock();
501
502 __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS);
503 kfree_skb(skb);
504 return -ENOMEM;
505 }
506 EXPORT_SYMBOL(ip_defrag);
507
ip_check_defrag(struct net * net,struct sk_buff * skb,u32 user)508 struct sk_buff *ip_check_defrag(struct net *net, struct sk_buff *skb, u32 user)
509 {
510 struct iphdr iph;
511 int netoff;
512 u32 len;
513
514 if (skb->protocol != htons(ETH_P_IP))
515 return skb;
516
517 netoff = skb_network_offset(skb);
518
519 if (skb_copy_bits(skb, netoff, &iph, sizeof(iph)) < 0)
520 return skb;
521
522 if (iph.ihl < 5 || iph.version != 4)
523 return skb;
524
525 len = ntohs(iph.tot_len);
526 if (skb->len < netoff + len || len < (iph.ihl * 4))
527 return skb;
528
529 if (ip_is_fragment(&iph)) {
530 skb = skb_share_check(skb, GFP_ATOMIC);
531 if (skb) {
532 if (!pskb_may_pull(skb, netoff + iph.ihl * 4)) {
533 kfree_skb(skb);
534 return NULL;
535 }
536 if (pskb_trim_rcsum(skb, netoff + len)) {
537 kfree_skb(skb);
538 return NULL;
539 }
540 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
541 if (ip_defrag(net, skb, user))
542 return NULL;
543 skb_clear_hash(skb);
544 }
545 }
546 return skb;
547 }
548 EXPORT_SYMBOL(ip_check_defrag);
549
550 #ifdef CONFIG_SYSCTL
551 static int dist_min;
552
553 static struct ctl_table ip4_frags_ns_ctl_table[] = {
554 {
555 .procname = "ipfrag_high_thresh",
556 .maxlen = sizeof(unsigned long),
557 .mode = 0644,
558 .proc_handler = proc_doulongvec_minmax,
559 },
560 {
561 .procname = "ipfrag_low_thresh",
562 .maxlen = sizeof(unsigned long),
563 .mode = 0644,
564 .proc_handler = proc_doulongvec_minmax,
565 },
566 {
567 .procname = "ipfrag_time",
568 .maxlen = sizeof(int),
569 .mode = 0644,
570 .proc_handler = proc_dointvec_jiffies,
571 },
572 {
573 .procname = "ipfrag_max_dist",
574 .maxlen = sizeof(int),
575 .mode = 0644,
576 .proc_handler = proc_dointvec_minmax,
577 .extra1 = &dist_min,
578 },
579 };
580
581 /* secret interval has been deprecated */
582 static int ip4_frags_secret_interval_unused;
583 static struct ctl_table ip4_frags_ctl_table[] = {
584 {
585 .procname = "ipfrag_secret_interval",
586 .data = &ip4_frags_secret_interval_unused,
587 .maxlen = sizeof(int),
588 .mode = 0644,
589 .proc_handler = proc_dointvec_jiffies,
590 },
591 };
592
ip4_frags_ns_ctl_register(struct net * net)593 static int __net_init ip4_frags_ns_ctl_register(struct net *net)
594 {
595 struct ctl_table *table;
596 struct ctl_table_header *hdr;
597
598 table = ip4_frags_ns_ctl_table;
599 if (!net_eq(net, &init_net)) {
600 table = kmemdup(table, sizeof(ip4_frags_ns_ctl_table), GFP_KERNEL);
601 if (!table)
602 goto err_alloc;
603
604 }
605 table[0].data = &net->ipv4.fqdir->high_thresh;
606 table[0].extra1 = &net->ipv4.fqdir->low_thresh;
607 table[1].data = &net->ipv4.fqdir->low_thresh;
608 table[1].extra2 = &net->ipv4.fqdir->high_thresh;
609 table[2].data = &net->ipv4.fqdir->timeout;
610 table[3].data = &net->ipv4.fqdir->max_dist;
611
612 hdr = register_net_sysctl_sz(net, "net/ipv4", table,
613 ARRAY_SIZE(ip4_frags_ns_ctl_table));
614 if (!hdr)
615 goto err_reg;
616
617 net->ipv4.frags_hdr = hdr;
618 return 0;
619
620 err_reg:
621 if (!net_eq(net, &init_net))
622 kfree(table);
623 err_alloc:
624 return -ENOMEM;
625 }
626
ip4_frags_ns_ctl_unregister(struct net * net)627 static void __net_exit ip4_frags_ns_ctl_unregister(struct net *net)
628 {
629 const struct ctl_table *table;
630
631 table = net->ipv4.frags_hdr->ctl_table_arg;
632 unregister_net_sysctl_table(net->ipv4.frags_hdr);
633 kfree(table);
634 }
635
ip4_frags_ctl_register(void)636 static void __init ip4_frags_ctl_register(void)
637 {
638 register_net_sysctl(&init_net, "net/ipv4", ip4_frags_ctl_table);
639 }
640 #else
ip4_frags_ns_ctl_register(struct net * net)641 static int ip4_frags_ns_ctl_register(struct net *net)
642 {
643 return 0;
644 }
645
ip4_frags_ns_ctl_unregister(struct net * net)646 static void ip4_frags_ns_ctl_unregister(struct net *net)
647 {
648 }
649
ip4_frags_ctl_register(void)650 static void __init ip4_frags_ctl_register(void)
651 {
652 }
653 #endif
654
ipv4_frags_init_net(struct net * net)655 static int __net_init ipv4_frags_init_net(struct net *net)
656 {
657 int res;
658
659 res = fqdir_init(&net->ipv4.fqdir, &ip4_frags, net);
660 if (res < 0)
661 return res;
662 /* Fragment cache limits.
663 *
664 * The fragment memory accounting code, (tries to) account for
665 * the real memory usage, by measuring both the size of frag
666 * queue struct (inet_frag_queue (ipv4:ipq/ipv6:frag_queue))
667 * and the SKB's truesize.
668 *
669 * A 64K fragment consumes 129736 bytes (44*2944)+200
670 * (1500 truesize == 2944, sizeof(struct ipq) == 200)
671 *
672 * We will commit 4MB at one time. Should we cross that limit
673 * we will prune down to 3MB, making room for approx 8 big 64K
674 * fragments 8x128k.
675 */
676 net->ipv4.fqdir->high_thresh = 4 * 1024 * 1024;
677 net->ipv4.fqdir->low_thresh = 3 * 1024 * 1024;
678 /*
679 * Important NOTE! Fragment queue must be destroyed before MSL expires.
680 * RFC791 is wrong proposing to prolongate timer each fragment arrival
681 * by TTL.
682 */
683 net->ipv4.fqdir->timeout = IP_FRAG_TIME;
684
685 net->ipv4.fqdir->max_dist = 64;
686
687 res = ip4_frags_ns_ctl_register(net);
688 if (res < 0)
689 fqdir_exit(net->ipv4.fqdir);
690 return res;
691 }
692
ipv4_frags_pre_exit_net(struct net * net)693 static void __net_exit ipv4_frags_pre_exit_net(struct net *net)
694 {
695 fqdir_pre_exit(net->ipv4.fqdir);
696 }
697
ipv4_frags_exit_net(struct net * net)698 static void __net_exit ipv4_frags_exit_net(struct net *net)
699 {
700 ip4_frags_ns_ctl_unregister(net);
701 fqdir_exit(net->ipv4.fqdir);
702 }
703
704 static struct pernet_operations ip4_frags_ops = {
705 .init = ipv4_frags_init_net,
706 .pre_exit = ipv4_frags_pre_exit_net,
707 .exit = ipv4_frags_exit_net,
708 };
709
710
ip4_key_hashfn(const void * data,u32 len,u32 seed)711 static u32 ip4_key_hashfn(const void *data, u32 len, u32 seed)
712 {
713 return jhash2(data,
714 sizeof(struct frag_v4_compare_key) / sizeof(u32), seed);
715 }
716
ip4_obj_hashfn(const void * data,u32 len,u32 seed)717 static u32 ip4_obj_hashfn(const void *data, u32 len, u32 seed)
718 {
719 const struct inet_frag_queue *fq = data;
720
721 return jhash2((const u32 *)&fq->key.v4,
722 sizeof(struct frag_v4_compare_key) / sizeof(u32), seed);
723 }
724
ip4_obj_cmpfn(struct rhashtable_compare_arg * arg,const void * ptr)725 static int ip4_obj_cmpfn(struct rhashtable_compare_arg *arg, const void *ptr)
726 {
727 const struct frag_v4_compare_key *key = arg->key;
728 const struct inet_frag_queue *fq = ptr;
729
730 return !!memcmp(&fq->key, key, sizeof(*key));
731 }
732
733 static const struct rhashtable_params ip4_rhash_params = {
734 .head_offset = offsetof(struct inet_frag_queue, node),
735 .key_offset = offsetof(struct inet_frag_queue, key),
736 .key_len = sizeof(struct frag_v4_compare_key),
737 .hashfn = ip4_key_hashfn,
738 .obj_hashfn = ip4_obj_hashfn,
739 .obj_cmpfn = ip4_obj_cmpfn,
740 .automatic_shrinking = true,
741 };
742
ipfrag_init(void)743 void __init ipfrag_init(void)
744 {
745 ip4_frags.constructor = ip4_frag_init;
746 ip4_frags.destructor = ip4_frag_free;
747 ip4_frags.qsize = sizeof(struct ipq);
748 ip4_frags.frag_expire = ip_expire;
749 ip4_frags.frags_cache_name = ip_frag_cache_name;
750 ip4_frags.rhash_params = ip4_rhash_params;
751 if (inet_frags_init(&ip4_frags))
752 panic("IP: failed to allocate ip4_frags cache\n");
753 ip4_frags_ctl_register();
754 register_pernet_subsys(&ip4_frags_ops);
755 }
756