1 /*-
2 * Copyright (c) 2015 Gleb Smirnoff <[email protected]>
3 * Copyright (c) 2015 Adrian Chadd <[email protected]>
4 * Copyright (c) 1982, 1986, 1988, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 * @(#)ip_input.c 8.2 (Berkeley) 1/4/94
32 */
33
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36
37 #include "opt_rss.h"
38
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/eventhandler.h>
42 #include <sys/kernel.h>
43 #include <sys/hash.h>
44 #include <sys/mbuf.h>
45 #include <sys/malloc.h>
46 #include <sys/limits.h>
47 #include <sys/lock.h>
48 #include <sys/mutex.h>
49 #include <sys/sysctl.h>
50 #include <sys/socket.h>
51
52 #include <net/if.h>
53 #include <net/if_var.h>
54 #include <net/rss_config.h>
55 #include <net/netisr.h>
56 #include <net/vnet.h>
57
58 #include <netinet/in.h>
59 #include <netinet/ip.h>
60 #include <netinet/ip_var.h>
61 #include <netinet/in_rss.h>
62 #ifdef MAC
63 #include <security/mac/mac_framework.h>
64 #endif
65
66 SYSCTL_DECL(_net_inet_ip);
67
68 /*
69 * Reassembly headers are stored in hash buckets.
70 */
71 #define IPREASS_NHASH_LOG2 10
72 #define IPREASS_NHASH (1 << IPREASS_NHASH_LOG2)
73 #define IPREASS_HMASK (IPREASS_NHASH - 1)
74
75 struct ipqbucket {
76 TAILQ_HEAD(ipqhead, ipq) head;
77 struct mtx lock;
78 int count;
79 };
80
81 VNET_DEFINE_STATIC(struct ipqbucket, ipq[IPREASS_NHASH]);
82 #define V_ipq VNET(ipq)
83 VNET_DEFINE_STATIC(uint32_t, ipq_hashseed);
84 #define V_ipq_hashseed VNET(ipq_hashseed)
85
86 #define IPQ_LOCK(i) mtx_lock(&V_ipq[i].lock)
87 #define IPQ_TRYLOCK(i) mtx_trylock(&V_ipq[i].lock)
88 #define IPQ_UNLOCK(i) mtx_unlock(&V_ipq[i].lock)
89 #define IPQ_LOCK_ASSERT(i) mtx_assert(&V_ipq[i].lock, MA_OWNED)
90
91 VNET_DEFINE_STATIC(int, ipreass_maxbucketsize);
92 #define V_ipreass_maxbucketsize VNET(ipreass_maxbucketsize)
93
94 void ipreass_init(void);
95 void ipreass_drain(void);
96 void ipreass_slowtimo(void);
97 #ifdef VIMAGE
98 void ipreass_destroy(void);
99 #endif
100 static int sysctl_maxfragpackets(SYSCTL_HANDLER_ARGS);
101 static int sysctl_maxfragbucketsize(SYSCTL_HANDLER_ARGS);
102 static void ipreass_zone_change(void *);
103 static void ipreass_drain_tomax(void);
104 static void ipq_free(struct ipqbucket *, struct ipq *);
105 static struct ipq * ipq_reuse(int);
106
107 static inline void
ipq_timeout(struct ipqbucket * bucket,struct ipq * fp)108 ipq_timeout(struct ipqbucket *bucket, struct ipq *fp)
109 {
110
111 IPSTAT_ADD(ips_fragtimeout, fp->ipq_nfrags);
112 ipq_free(bucket, fp);
113 }
114
115 static inline void
ipq_drop(struct ipqbucket * bucket,struct ipq * fp)116 ipq_drop(struct ipqbucket *bucket, struct ipq *fp)
117 {
118
119 IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags);
120 ipq_free(bucket, fp);
121 }
122
123 /*
124 * By default, limit the number of IP fragments across all reassembly
125 * queues to 1/32 of the total number of mbuf clusters.
126 *
127 * Limit the total number of reassembly queues per VNET to the
128 * IP fragment limit, but ensure the limit will not allow any bucket
129 * to grow above 100 items. (The bucket limit is
130 * IP_MAXFRAGPACKETS / (IPREASS_NHASH / 2), so the 50 is the correct
131 * multiplier to reach a 100-item limit.)
132 * The 100-item limit was chosen as brief testing seems to show that
133 * this produces "reasonable" performance on some subset of systems
134 * under DoS attack.
135 */
136 #define IP_MAXFRAGS (nmbclusters / 32)
137 #define IP_MAXFRAGPACKETS (imin(IP_MAXFRAGS, IPREASS_NHASH * 50))
138
139 static int maxfrags;
140 static volatile u_int nfrags;
141 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfrags, CTLFLAG_RW,
142 &maxfrags, 0,
143 "Maximum number of IPv4 fragments allowed across all reassembly queues");
144 SYSCTL_UINT(_net_inet_ip, OID_AUTO, curfrags, CTLFLAG_RD,
145 __DEVOLATILE(u_int *, &nfrags), 0,
146 "Current number of IPv4 fragments across all reassembly queues");
147
148 VNET_DEFINE_STATIC(uma_zone_t, ipq_zone);
149 #define V_ipq_zone VNET(ipq_zone)
150 SYSCTL_PROC(_net_inet_ip, OID_AUTO, maxfragpackets,
151 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
152 NULL, 0, sysctl_maxfragpackets, "I",
153 "Maximum number of IPv4 fragment reassembly queue entries");
154 SYSCTL_UMA_CUR(_net_inet_ip, OID_AUTO, fragpackets, CTLFLAG_VNET,
155 &VNET_NAME(ipq_zone),
156 "Current number of IPv4 fragment reassembly queue entries");
157
158 VNET_DEFINE_STATIC(int, noreass);
159 #define V_noreass VNET(noreass)
160
161 VNET_DEFINE_STATIC(int, maxfragsperpacket);
162 #define V_maxfragsperpacket VNET(maxfragsperpacket)
163 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_VNET | CTLFLAG_RW,
164 &VNET_NAME(maxfragsperpacket), 0,
165 "Maximum number of IPv4 fragments allowed per packet");
166 SYSCTL_PROC(_net_inet_ip, OID_AUTO, maxfragbucketsize,
167 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_MPSAFE | CTLFLAG_RW, NULL, 0,
168 sysctl_maxfragbucketsize, "I",
169 "Maximum number of IPv4 fragment reassembly queue entries per bucket");
170
171 /*
172 * Take incoming datagram fragment and try to reassemble it into
173 * whole datagram. If the argument is the first fragment or one
174 * in between the function will return NULL and store the mbuf
175 * in the fragment chain. If the argument is the last fragment
176 * the packet will be reassembled and the pointer to the new
177 * mbuf returned for further processing. Only m_tags attached
178 * to the first packet/fragment are preserved.
179 * The IP header is *NOT* adjusted out of iplen.
180 */
181 #define M_IP_FRAG M_PROTO9
182 struct mbuf *
ip_reass(struct mbuf * m)183 ip_reass(struct mbuf *m)
184 {
185 struct ip *ip;
186 struct mbuf *p, *q, *nq, *t;
187 struct ipq *fp;
188 struct ifnet *srcifp;
189 struct ipqhead *head;
190 int i, hlen, next, tmpmax;
191 u_int8_t ecn, ecn0;
192 uint32_t hash, hashkey[3];
193 #ifdef RSS
194 uint32_t rss_hash, rss_type;
195 #endif
196
197 /*
198 * If no reassembling or maxfragsperpacket are 0,
199 * never accept fragments.
200 * Also, drop packet if it would exceed the maximum
201 * number of fragments.
202 */
203 tmpmax = maxfrags;
204 if (V_noreass == 1 || V_maxfragsperpacket == 0 ||
205 (tmpmax >= 0 && atomic_load_int(&nfrags) >= (u_int)tmpmax)) {
206 IPSTAT_INC(ips_fragments);
207 IPSTAT_INC(ips_fragdropped);
208 m_freem(m);
209 return (NULL);
210 }
211
212 ip = mtod(m, struct ip *);
213 hlen = ip->ip_hl << 2;
214
215 /*
216 * Adjust ip_len to not reflect header,
217 * convert offset of this to bytes.
218 */
219 ip->ip_len = htons(ntohs(ip->ip_len) - hlen);
220 /*
221 * Make sure that fragments have a data length
222 * that's a non-zero multiple of 8 bytes, unless
223 * this is the last fragment.
224 */
225 if (ip->ip_len == htons(0) ||
226 ((ip->ip_off & htons(IP_MF)) && (ntohs(ip->ip_len) & 0x7) != 0)) {
227 IPSTAT_INC(ips_toosmall); /* XXX */
228 IPSTAT_INC(ips_fragdropped);
229 m_freem(m);
230 return (NULL);
231 }
232 if (ip->ip_off & htons(IP_MF))
233 m->m_flags |= M_IP_FRAG;
234 else
235 m->m_flags &= ~M_IP_FRAG;
236 ip->ip_off = htons(ntohs(ip->ip_off) << 3);
237
238 /*
239 * Make sure the fragment lies within a packet of valid size.
240 */
241 if (ntohs(ip->ip_len) + ntohs(ip->ip_off) > IP_MAXPACKET) {
242 IPSTAT_INC(ips_toolong);
243 IPSTAT_INC(ips_fragdropped);
244 m_freem(m);
245 return (NULL);
246 }
247
248 /*
249 * Store receive network interface pointer for later.
250 */
251 srcifp = m->m_pkthdr.rcvif;
252
253 /*
254 * Attempt reassembly; if it succeeds, proceed.
255 * ip_reass() will return a different mbuf.
256 */
257 IPSTAT_INC(ips_fragments);
258 m->m_pkthdr.PH_loc.ptr = ip;
259
260 /*
261 * Presence of header sizes in mbufs
262 * would confuse code below.
263 */
264 m->m_data += hlen;
265 m->m_len -= hlen;
266
267 hashkey[0] = ip->ip_src.s_addr;
268 hashkey[1] = ip->ip_dst.s_addr;
269 hashkey[2] = (uint32_t)ip->ip_p << 16;
270 hashkey[2] += ip->ip_id;
271 hash = jenkins_hash32(hashkey, nitems(hashkey), V_ipq_hashseed);
272 hash &= IPREASS_HMASK;
273 head = &V_ipq[hash].head;
274 IPQ_LOCK(hash);
275
276 /*
277 * Look for queue of fragments
278 * of this datagram.
279 */
280 TAILQ_FOREACH(fp, head, ipq_list)
281 if (ip->ip_id == fp->ipq_id &&
282 ip->ip_src.s_addr == fp->ipq_src.s_addr &&
283 ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
284 #ifdef MAC
285 mac_ipq_match(m, fp) &&
286 #endif
287 ip->ip_p == fp->ipq_p)
288 break;
289 /*
290 * If first fragment to arrive, create a reassembly queue.
291 */
292 if (fp == NULL) {
293 if (V_ipq[hash].count < V_ipreass_maxbucketsize)
294 fp = uma_zalloc(V_ipq_zone, M_NOWAIT);
295 if (fp == NULL)
296 fp = ipq_reuse(hash);
297 if (fp == NULL)
298 goto dropfrag;
299 #ifdef MAC
300 if (mac_ipq_init(fp, M_NOWAIT) != 0) {
301 uma_zfree(V_ipq_zone, fp);
302 fp = NULL;
303 goto dropfrag;
304 }
305 mac_ipq_create(m, fp);
306 #endif
307 TAILQ_INSERT_HEAD(head, fp, ipq_list);
308 V_ipq[hash].count++;
309 fp->ipq_nfrags = 1;
310 atomic_add_int(&nfrags, 1);
311 fp->ipq_ttl = IPFRAGTTL;
312 fp->ipq_p = ip->ip_p;
313 fp->ipq_id = ip->ip_id;
314 fp->ipq_src = ip->ip_src;
315 fp->ipq_dst = ip->ip_dst;
316 fp->ipq_frags = m;
317 if (m->m_flags & M_IP_FRAG)
318 fp->ipq_maxoff = -1;
319 else
320 fp->ipq_maxoff = ntohs(ip->ip_off) + ntohs(ip->ip_len);
321 m->m_nextpkt = NULL;
322 goto done;
323 } else {
324 /*
325 * If we already saw the last fragment, make sure
326 * this fragment's offset looks sane. Otherwise, if
327 * this is the last fragment, record its endpoint.
328 */
329 if (fp->ipq_maxoff > 0) {
330 i = ntohs(ip->ip_off) + ntohs(ip->ip_len);
331 if (((m->m_flags & M_IP_FRAG) && i >= fp->ipq_maxoff) ||
332 ((m->m_flags & M_IP_FRAG) == 0 &&
333 i != fp->ipq_maxoff)) {
334 fp = NULL;
335 goto dropfrag;
336 }
337 } else if ((m->m_flags & M_IP_FRAG) == 0)
338 fp->ipq_maxoff = ntohs(ip->ip_off) + ntohs(ip->ip_len);
339 fp->ipq_nfrags++;
340 atomic_add_int(&nfrags, 1);
341 #ifdef MAC
342 mac_ipq_update(m, fp);
343 #endif
344 }
345
346 #define GETIP(m) ((struct ip*)((m)->m_pkthdr.PH_loc.ptr))
347
348 /*
349 * Handle ECN by comparing this segment with the first one;
350 * if CE is set, do not lose CE.
351 * drop if CE and not-ECT are mixed for the same packet.
352 */
353 ecn = ip->ip_tos & IPTOS_ECN_MASK;
354 ecn0 = GETIP(fp->ipq_frags)->ip_tos & IPTOS_ECN_MASK;
355 if (ecn == IPTOS_ECN_CE) {
356 if (ecn0 == IPTOS_ECN_NOTECT)
357 goto dropfrag;
358 if (ecn0 != IPTOS_ECN_CE)
359 GETIP(fp->ipq_frags)->ip_tos |= IPTOS_ECN_CE;
360 }
361 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT)
362 goto dropfrag;
363
364 /*
365 * Find a segment which begins after this one does.
366 */
367 for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt)
368 if (ntohs(GETIP(q)->ip_off) > ntohs(ip->ip_off))
369 break;
370
371 /*
372 * If there is a preceding segment, it may provide some of
373 * our data already. If so, drop the data from the incoming
374 * segment. If it provides all of our data, drop us, otherwise
375 * stick new segment in the proper place.
376 *
377 * If some of the data is dropped from the preceding
378 * segment, then it's checksum is invalidated.
379 */
380 if (p) {
381 i = ntohs(GETIP(p)->ip_off) + ntohs(GETIP(p)->ip_len) -
382 ntohs(ip->ip_off);
383 if (i > 0) {
384 if (i >= ntohs(ip->ip_len))
385 goto dropfrag;
386 m_adj(m, i);
387 m->m_pkthdr.csum_flags = 0;
388 ip->ip_off = htons(ntohs(ip->ip_off) + i);
389 ip->ip_len = htons(ntohs(ip->ip_len) - i);
390 }
391 m->m_nextpkt = p->m_nextpkt;
392 p->m_nextpkt = m;
393 } else {
394 m->m_nextpkt = fp->ipq_frags;
395 fp->ipq_frags = m;
396 }
397
398 /*
399 * While we overlap succeeding segments trim them or,
400 * if they are completely covered, dequeue them.
401 */
402 for (; q != NULL && ntohs(ip->ip_off) + ntohs(ip->ip_len) >
403 ntohs(GETIP(q)->ip_off); q = nq) {
404 i = (ntohs(ip->ip_off) + ntohs(ip->ip_len)) -
405 ntohs(GETIP(q)->ip_off);
406 if (i < ntohs(GETIP(q)->ip_len)) {
407 GETIP(q)->ip_len = htons(ntohs(GETIP(q)->ip_len) - i);
408 GETIP(q)->ip_off = htons(ntohs(GETIP(q)->ip_off) + i);
409 m_adj(q, i);
410 q->m_pkthdr.csum_flags = 0;
411 break;
412 }
413 nq = q->m_nextpkt;
414 m->m_nextpkt = nq;
415 IPSTAT_INC(ips_fragdropped);
416 fp->ipq_nfrags--;
417 atomic_subtract_int(&nfrags, 1);
418 m_freem(q);
419 }
420
421 /*
422 * Check for complete reassembly and perform frag per packet
423 * limiting.
424 *
425 * Frag limiting is performed here so that the nth frag has
426 * a chance to complete the packet before we drop the packet.
427 * As a result, n+1 frags are actually allowed per packet, but
428 * only n will ever be stored. (n = maxfragsperpacket.)
429 *
430 */
431 next = 0;
432 for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) {
433 if (ntohs(GETIP(q)->ip_off) != next) {
434 if (fp->ipq_nfrags > V_maxfragsperpacket)
435 ipq_drop(&V_ipq[hash], fp);
436 goto done;
437 }
438 next += ntohs(GETIP(q)->ip_len);
439 }
440 /* Make sure the last packet didn't have the IP_MF flag */
441 if (p->m_flags & M_IP_FRAG) {
442 if (fp->ipq_nfrags > V_maxfragsperpacket)
443 ipq_drop(&V_ipq[hash], fp);
444 goto done;
445 }
446
447 /*
448 * Reassembly is complete. Make sure the packet is a sane size.
449 */
450 q = fp->ipq_frags;
451 ip = GETIP(q);
452 if (next + (ip->ip_hl << 2) > IP_MAXPACKET) {
453 IPSTAT_INC(ips_toolong);
454 ipq_drop(&V_ipq[hash], fp);
455 goto done;
456 }
457
458 /*
459 * Concatenate fragments.
460 */
461 m = q;
462 t = m->m_next;
463 m->m_next = NULL;
464 m_cat(m, t);
465 nq = q->m_nextpkt;
466 q->m_nextpkt = NULL;
467 for (q = nq; q != NULL; q = nq) {
468 nq = q->m_nextpkt;
469 q->m_nextpkt = NULL;
470 m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags;
471 m->m_pkthdr.csum_data += q->m_pkthdr.csum_data;
472 m_demote_pkthdr(q);
473 m_cat(m, q);
474 }
475 /*
476 * In order to do checksumming faster we do 'end-around carry' here
477 * (and not in for{} loop), though it implies we are not going to
478 * reassemble more than 64k fragments.
479 */
480 while (m->m_pkthdr.csum_data & 0xffff0000)
481 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) +
482 (m->m_pkthdr.csum_data >> 16);
483 atomic_subtract_int(&nfrags, fp->ipq_nfrags);
484 #ifdef MAC
485 mac_ipq_reassemble(fp, m);
486 mac_ipq_destroy(fp);
487 #endif
488
489 /*
490 * Create header for new ip packet by modifying header of first
491 * packet; dequeue and discard fragment reassembly header.
492 * Make header visible.
493 */
494 ip->ip_len = htons((ip->ip_hl << 2) + next);
495 ip->ip_src = fp->ipq_src;
496 ip->ip_dst = fp->ipq_dst;
497 TAILQ_REMOVE(head, fp, ipq_list);
498 V_ipq[hash].count--;
499 uma_zfree(V_ipq_zone, fp);
500 m->m_len += (ip->ip_hl << 2);
501 m->m_data -= (ip->ip_hl << 2);
502 /* some debugging cruft by sklower, below, will go away soon */
503 if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
504 m_fixhdr(m);
505 /* set valid receive interface pointer */
506 m->m_pkthdr.rcvif = srcifp;
507 }
508 IPSTAT_INC(ips_reassembled);
509 IPQ_UNLOCK(hash);
510
511 #ifdef RSS
512 /*
513 * Query the RSS layer for the flowid / flowtype for the
514 * mbuf payload.
515 *
516 * For now, just assume we have to calculate a new one.
517 * Later on we should check to see if the assigned flowid matches
518 * what RSS wants for the given IP protocol and if so, just keep it.
519 *
520 * We then queue into the relevant netisr so it can be dispatched
521 * to the correct CPU.
522 *
523 * Note - this may return 1, which means the flowid in the mbuf
524 * is correct for the configured RSS hash types and can be used.
525 */
526 if (rss_mbuf_software_hash_v4(m, 0, &rss_hash, &rss_type) == 0) {
527 m->m_pkthdr.flowid = rss_hash;
528 M_HASHTYPE_SET(m, rss_type);
529 }
530
531 /*
532 * Queue/dispatch for reprocessing.
533 *
534 * Note: this is much slower than just handling the frame in the
535 * current receive context. It's likely worth investigating
536 * why this is.
537 */
538 netisr_dispatch(NETISR_IP_DIRECT, m);
539 return (NULL);
540 #endif
541
542 /* Handle in-line */
543 return (m);
544
545 dropfrag:
546 IPSTAT_INC(ips_fragdropped);
547 if (fp != NULL) {
548 fp->ipq_nfrags--;
549 atomic_subtract_int(&nfrags, 1);
550 }
551 m_freem(m);
552 done:
553 IPQ_UNLOCK(hash);
554 return (NULL);
555
556 #undef GETIP
557 }
558
559 /*
560 * Initialize IP reassembly structures.
561 */
562 void
ipreass_init(void)563 ipreass_init(void)
564 {
565 int max;
566
567 for (int i = 0; i < IPREASS_NHASH; i++) {
568 TAILQ_INIT(&V_ipq[i].head);
569 mtx_init(&V_ipq[i].lock, "IP reassembly", NULL,
570 MTX_DEF | MTX_DUPOK);
571 V_ipq[i].count = 0;
572 }
573 V_ipq_hashseed = arc4random();
574 V_maxfragsperpacket = 16;
575 V_ipq_zone = uma_zcreate("ipq", sizeof(struct ipq), NULL, NULL, NULL,
576 NULL, UMA_ALIGN_PTR, 0);
577 max = IP_MAXFRAGPACKETS;
578 max = uma_zone_set_max(V_ipq_zone, max);
579 V_ipreass_maxbucketsize = imax(max / (IPREASS_NHASH / 2), 1);
580
581 if (IS_DEFAULT_VNET(curvnet)) {
582 maxfrags = IP_MAXFRAGS;
583 EVENTHANDLER_REGISTER(nmbclusters_change, ipreass_zone_change,
584 NULL, EVENTHANDLER_PRI_ANY);
585 }
586 }
587
588 /*
589 * If a timer expires on a reassembly queue, discard it.
590 */
591 void
ipreass_slowtimo(void)592 ipreass_slowtimo(void)
593 {
594 struct ipq *fp, *tmp;
595
596 for (int i = 0; i < IPREASS_NHASH; i++) {
597 IPQ_LOCK(i);
598 TAILQ_FOREACH_SAFE(fp, &V_ipq[i].head, ipq_list, tmp)
599 if (--fp->ipq_ttl == 0)
600 ipq_timeout(&V_ipq[i], fp);
601 IPQ_UNLOCK(i);
602 }
603 }
604
605 /*
606 * Drain off all datagram fragments.
607 */
608 void
ipreass_drain(void)609 ipreass_drain(void)
610 {
611
612 for (int i = 0; i < IPREASS_NHASH; i++) {
613 IPQ_LOCK(i);
614 while(!TAILQ_EMPTY(&V_ipq[i].head))
615 ipq_drop(&V_ipq[i], TAILQ_FIRST(&V_ipq[i].head));
616 KASSERT(V_ipq[i].count == 0,
617 ("%s: V_ipq[%d] count %d (V_ipq=%p)", __func__, i,
618 V_ipq[i].count, V_ipq));
619 IPQ_UNLOCK(i);
620 }
621 }
622
623 /*
624 * Drain off all datagram fragments belonging to
625 * the given network interface.
626 */
627 static void
ipreass_cleanup(void * arg __unused,struct ifnet * ifp)628 ipreass_cleanup(void *arg __unused, struct ifnet *ifp)
629 {
630 struct ipq *fp, *temp;
631 struct mbuf *m;
632 int i;
633
634 KASSERT(ifp != NULL, ("%s: ifp is NULL", __func__));
635
636 CURVNET_SET_QUIET(ifp->if_vnet);
637
638 /*
639 * Skip processing if IPv4 reassembly is not initialised or
640 * torn down by ipreass_destroy().
641 */
642 if (V_ipq_zone == NULL) {
643 CURVNET_RESTORE();
644 return;
645 }
646
647 for (i = 0; i < IPREASS_NHASH; i++) {
648 IPQ_LOCK(i);
649 /* Scan fragment list. */
650 TAILQ_FOREACH_SAFE(fp, &V_ipq[i].head, ipq_list, temp) {
651 for (m = fp->ipq_frags; m != NULL; m = m->m_nextpkt) {
652 /* clear no longer valid rcvif pointer */
653 if (m->m_pkthdr.rcvif == ifp)
654 m->m_pkthdr.rcvif = NULL;
655 }
656 }
657 IPQ_UNLOCK(i);
658 }
659 CURVNET_RESTORE();
660 }
661 EVENTHANDLER_DEFINE(ifnet_departure_event, ipreass_cleanup, NULL, 0);
662
663 #ifdef VIMAGE
664 /*
665 * Destroy IP reassembly structures.
666 */
667 void
ipreass_destroy(void)668 ipreass_destroy(void)
669 {
670
671 ipreass_drain();
672 uma_zdestroy(V_ipq_zone);
673 V_ipq_zone = NULL;
674 for (int i = 0; i < IPREASS_NHASH; i++)
675 mtx_destroy(&V_ipq[i].lock);
676 }
677 #endif
678
679 /*
680 * After maxnipq has been updated, propagate the change to UMA. The UMA zone
681 * max has slightly different semantics than the sysctl, for historical
682 * reasons.
683 */
684 static void
ipreass_drain_tomax(void)685 ipreass_drain_tomax(void)
686 {
687 struct ipq *fp;
688 int target;
689
690 /*
691 * Make sure each bucket is under the new limit. If
692 * necessary, drop enough of the oldest elements from
693 * each bucket to get under the new limit.
694 */
695 for (int i = 0; i < IPREASS_NHASH; i++) {
696 IPQ_LOCK(i);
697 while (V_ipq[i].count > V_ipreass_maxbucketsize &&
698 (fp = TAILQ_LAST(&V_ipq[i].head, ipqhead)) != NULL)
699 ipq_timeout(&V_ipq[i], fp);
700 IPQ_UNLOCK(i);
701 }
702
703 /*
704 * If we are over the maximum number of fragments,
705 * drain off enough to get down to the new limit,
706 * stripping off last elements on queues. Every
707 * run we strip the oldest element from each bucket.
708 */
709 target = uma_zone_get_max(V_ipq_zone);
710 while (uma_zone_get_cur(V_ipq_zone) > target) {
711 for (int i = 0; i < IPREASS_NHASH; i++) {
712 IPQ_LOCK(i);
713 fp = TAILQ_LAST(&V_ipq[i].head, ipqhead);
714 if (fp != NULL)
715 ipq_timeout(&V_ipq[i], fp);
716 IPQ_UNLOCK(i);
717 }
718 }
719 }
720
721 static void
ipreass_zone_change(void * tag)722 ipreass_zone_change(void *tag)
723 {
724 VNET_ITERATOR_DECL(vnet_iter);
725 int max;
726
727 maxfrags = IP_MAXFRAGS;
728 max = IP_MAXFRAGPACKETS;
729 VNET_LIST_RLOCK_NOSLEEP();
730 VNET_FOREACH(vnet_iter) {
731 CURVNET_SET(vnet_iter);
732 max = uma_zone_set_max(V_ipq_zone, max);
733 V_ipreass_maxbucketsize = imax(max / (IPREASS_NHASH / 2), 1);
734 ipreass_drain_tomax();
735 CURVNET_RESTORE();
736 }
737 VNET_LIST_RUNLOCK_NOSLEEP();
738 }
739
740 /*
741 * Change the limit on the UMA zone, or disable the fragment allocation
742 * at all. Since 0 and -1 is a special values here, we need our own handler,
743 * instead of sysctl_handle_uma_zone_max().
744 */
745 static int
sysctl_maxfragpackets(SYSCTL_HANDLER_ARGS)746 sysctl_maxfragpackets(SYSCTL_HANDLER_ARGS)
747 {
748 int error, max;
749
750 if (V_noreass == 0) {
751 max = uma_zone_get_max(V_ipq_zone);
752 if (max == 0)
753 max = -1;
754 } else
755 max = 0;
756 error = sysctl_handle_int(oidp, &max, 0, req);
757 if (error || !req->newptr)
758 return (error);
759 if (max > 0) {
760 /*
761 * XXXRW: Might be a good idea to sanity check the argument
762 * and place an extreme upper bound.
763 */
764 max = uma_zone_set_max(V_ipq_zone, max);
765 V_ipreass_maxbucketsize = imax(max / (IPREASS_NHASH / 2), 1);
766 ipreass_drain_tomax();
767 V_noreass = 0;
768 } else if (max == 0) {
769 V_noreass = 1;
770 ipreass_drain();
771 } else if (max == -1) {
772 V_noreass = 0;
773 uma_zone_set_max(V_ipq_zone, 0);
774 V_ipreass_maxbucketsize = INT_MAX;
775 } else
776 return (EINVAL);
777 return (0);
778 }
779
780 /*
781 * Seek for old fragment queue header that can be reused. Try to
782 * reuse a header from currently locked hash bucket.
783 */
784 static struct ipq *
ipq_reuse(int start)785 ipq_reuse(int start)
786 {
787 struct ipq *fp;
788 int bucket, i;
789
790 IPQ_LOCK_ASSERT(start);
791
792 for (i = 0; i < IPREASS_NHASH; i++) {
793 bucket = (start + i) % IPREASS_NHASH;
794 if (bucket != start && IPQ_TRYLOCK(bucket) == 0)
795 continue;
796 fp = TAILQ_LAST(&V_ipq[bucket].head, ipqhead);
797 if (fp) {
798 struct mbuf *m;
799
800 IPSTAT_ADD(ips_fragtimeout, fp->ipq_nfrags);
801 atomic_subtract_int(&nfrags, fp->ipq_nfrags);
802 while (fp->ipq_frags) {
803 m = fp->ipq_frags;
804 fp->ipq_frags = m->m_nextpkt;
805 m_freem(m);
806 }
807 TAILQ_REMOVE(&V_ipq[bucket].head, fp, ipq_list);
808 V_ipq[bucket].count--;
809 if (bucket != start)
810 IPQ_UNLOCK(bucket);
811 break;
812 }
813 if (bucket != start)
814 IPQ_UNLOCK(bucket);
815 }
816 IPQ_LOCK_ASSERT(start);
817 return (fp);
818 }
819
820 /*
821 * Free a fragment reassembly header and all associated datagrams.
822 */
823 static void
ipq_free(struct ipqbucket * bucket,struct ipq * fp)824 ipq_free(struct ipqbucket *bucket, struct ipq *fp)
825 {
826 struct mbuf *q;
827
828 atomic_subtract_int(&nfrags, fp->ipq_nfrags);
829 while (fp->ipq_frags) {
830 q = fp->ipq_frags;
831 fp->ipq_frags = q->m_nextpkt;
832 m_freem(q);
833 }
834 TAILQ_REMOVE(&bucket->head, fp, ipq_list);
835 bucket->count--;
836 uma_zfree(V_ipq_zone, fp);
837 }
838
839 /*
840 * Get or set the maximum number of reassembly queues per bucket.
841 */
842 static int
sysctl_maxfragbucketsize(SYSCTL_HANDLER_ARGS)843 sysctl_maxfragbucketsize(SYSCTL_HANDLER_ARGS)
844 {
845 int error, max;
846
847 max = V_ipreass_maxbucketsize;
848 error = sysctl_handle_int(oidp, &max, 0, req);
849 if (error || !req->newptr)
850 return (error);
851 if (max <= 0)
852 return (EINVAL);
853 V_ipreass_maxbucketsize = max;
854 ipreass_drain_tomax();
855 return (0);
856 }
857