1 /*-
2 * Copyright (c) 2015 Gleb Smirnoff <glebius@FreeBSD.org>
3 * Copyright (c) 2015 Adrian Chadd <adrian@FreeBSD.org>
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
32 #include <sys/cdefs.h>
33 #include "opt_rss.h"
34
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/eventhandler.h>
38 #include <sys/kernel.h>
39 #include <sys/hash.h>
40 #include <sys/mbuf.h>
41 #include <sys/malloc.h>
42 #include <sys/limits.h>
43 #include <sys/lock.h>
44 #include <sys/mutex.h>
45 #include <sys/sysctl.h>
46 #include <sys/socket.h>
47
48 #include <net/if.h>
49 #include <net/if_var.h>
50 #include <net/if_private.h>
51 #include <net/rss_config.h>
52 #include <net/netisr.h>
53 #include <net/vnet.h>
54
55 #include <netinet/in.h>
56 #include <netinet/ip.h>
57 #include <netinet/ip_var.h>
58 #include <netinet/in_rss.h>
59 #ifdef MAC
60 #include <security/mac/mac_framework.h>
61 #endif
62
63 SYSCTL_DECL(_net_inet_ip);
64
65 /*
66 * Reassembly headers are stored in hash buckets.
67 */
68 #define IPREASS_NHASH_LOG2 10
69 #define IPREASS_NHASH (1 << IPREASS_NHASH_LOG2)
70 #define IPREASS_HMASK (V_ipq_hashsize - 1)
71
72 struct ipqbucket {
73 TAILQ_HEAD(ipqhead, ipq) head;
74 struct mtx lock;
75 struct callout timer;
76 #ifdef VIMAGE
77 struct vnet *vnet;
78 #endif
79 int count;
80 };
81
82 VNET_DEFINE_STATIC(struct ipqbucket *, ipq);
83 #define V_ipq VNET(ipq)
84 VNET_DEFINE_STATIC(uint32_t, ipq_hashseed);
85 #define V_ipq_hashseed VNET(ipq_hashseed)
86 VNET_DEFINE_STATIC(uint32_t, ipq_hashsize);
87 #define V_ipq_hashsize VNET(ipq_hashsize)
88
89 #define IPQ_LOCK(i) mtx_lock(&V_ipq[i].lock)
90 #define IPQ_TRYLOCK(i) mtx_trylock(&V_ipq[i].lock)
91 #define IPQ_UNLOCK(i) mtx_unlock(&V_ipq[i].lock)
92 #define IPQ_LOCK_ASSERT(i) mtx_assert(&V_ipq[i].lock, MA_OWNED)
93 #define IPQ_BUCKET_LOCK_ASSERT(b) mtx_assert(&(b)->lock, MA_OWNED)
94
95 VNET_DEFINE_STATIC(int, ipreass_maxbucketsize);
96 #define V_ipreass_maxbucketsize VNET(ipreass_maxbucketsize)
97
98 void ipreass_init(void);
99 void ipreass_vnet_init(void);
100 #ifdef VIMAGE
101 void ipreass_destroy(void);
102 #endif
103 static int sysctl_maxfragpackets(SYSCTL_HANDLER_ARGS);
104 static int sysctl_maxfragbucketsize(SYSCTL_HANDLER_ARGS);
105 static int sysctl_fragttl(SYSCTL_HANDLER_ARGS);
106 static void ipreass_zone_change(void *);
107 static void ipreass_drain_tomax(void);
108 static void ipq_free(struct ipqbucket *, struct ipq *);
109 static struct ipq * ipq_reuse(int);
110 static void ipreass_callout(void *);
111 static void ipreass_reschedule(struct ipqbucket *);
112
113 static inline void
ipq_timeout(struct ipqbucket * bucket,struct ipq * fp)114 ipq_timeout(struct ipqbucket *bucket, struct ipq *fp)
115 {
116
117 IPSTAT_ADD(ips_fragtimeout, fp->ipq_nfrags);
118 ipq_free(bucket, fp);
119 }
120
121 static inline void
ipq_drop(struct ipqbucket * bucket,struct ipq * fp)122 ipq_drop(struct ipqbucket *bucket, struct ipq *fp)
123 {
124
125 IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags);
126 ipq_free(bucket, fp);
127 ipreass_reschedule(bucket);
128 }
129
130 /*
131 * By default, limit the number of IP fragments across all reassembly
132 * queues to 1/32 of the total number of mbuf clusters.
133 *
134 * Limit the total number of reassembly queues per VNET to the
135 * IP fragment limit, but ensure the limit will not allow any bucket
136 * to grow above 100 items. (The bucket limit is
137 * IP_MAXFRAGPACKETS / (V_ipq_hashsize / 2), so the 50 is the correct
138 * multiplier to reach a 100-item limit.)
139 * The 100-item limit was chosen as brief testing seems to show that
140 * this produces "reasonable" performance on some subset of systems
141 * under DoS attack.
142 */
143 #define IP_MAXFRAGS (nmbclusters / 32)
144 #define IP_MAXFRAGPACKETS (imin(IP_MAXFRAGS, V_ipq_hashsize * 50))
145
146 static int maxfrags;
147 static u_int __exclusive_cache_line nfrags;
148 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfrags, CTLFLAG_RW,
149 &maxfrags, 0,
150 "Maximum number of IPv4 fragments allowed across all reassembly queues");
151 SYSCTL_UINT(_net_inet_ip, OID_AUTO, curfrags, CTLFLAG_RD,
152 &nfrags, 0,
153 "Current number of IPv4 fragments across all reassembly queues");
154
155 VNET_DEFINE_STATIC(uma_zone_t, ipq_zone);
156 #define V_ipq_zone VNET(ipq_zone)
157
158 SYSCTL_UINT(_net_inet_ip, OID_AUTO, reass_hashsize,
159 CTLFLAG_VNET | CTLFLAG_RDTUN, &VNET_NAME(ipq_hashsize), 0,
160 "Size of IP fragment reassembly hashtable");
161
162 SYSCTL_PROC(_net_inet_ip, OID_AUTO, maxfragpackets,
163 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
164 NULL, 0, sysctl_maxfragpackets, "I",
165 "Maximum number of IPv4 fragment reassembly queue entries");
166 SYSCTL_UMA_CUR(_net_inet_ip, OID_AUTO, fragpackets, CTLFLAG_VNET,
167 &VNET_NAME(ipq_zone),
168 "Current number of IPv4 fragment reassembly queue entries");
169
170 VNET_DEFINE_STATIC(int, noreass);
171 #define V_noreass VNET(noreass)
172
173 VNET_DEFINE_STATIC(int, maxfragsperpacket);
174 #define V_maxfragsperpacket VNET(maxfragsperpacket)
175 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_VNET | CTLFLAG_RW,
176 &VNET_NAME(maxfragsperpacket), 0,
177 "Maximum number of IPv4 fragments allowed per packet");
178 SYSCTL_PROC(_net_inet_ip, OID_AUTO, maxfragbucketsize,
179 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_MPSAFE | CTLFLAG_RW, NULL, 0,
180 sysctl_maxfragbucketsize, "I",
181 "Maximum number of IPv4 fragment reassembly queue entries per bucket");
182
183 VNET_DEFINE_STATIC(u_int, ipfragttl) = 30;
184 #define V_ipfragttl VNET(ipfragttl)
185 SYSCTL_PROC(_net_inet_ip, OID_AUTO, fragttl, CTLTYPE_INT | CTLFLAG_RW |
186 CTLFLAG_MPSAFE | CTLFLAG_VNET, NULL, 0, sysctl_fragttl, "IU",
187 "IP fragment life time on reassembly queue (seconds)");
188
189 /*
190 * Take incoming datagram fragment and try to reassemble it into
191 * whole datagram. If the argument is the first fragment or one
192 * in between the function will return NULL and store the mbuf
193 * in the fragment chain. If the argument is the last fragment
194 * the packet will be reassembled and the pointer to the new
195 * mbuf returned for further processing. Only m_tags attached
196 * to the first packet/fragment are preserved.
197 * The IP header is *NOT* adjusted out of iplen.
198 */
199 #define M_IP_FRAG M_PROTO9
200 struct mbuf *
ip_reass(struct mbuf * m)201 ip_reass(struct mbuf *m)
202 {
203 struct ip *ip;
204 struct mbuf *p, *q, *nq, *t;
205 struct ipq *fp;
206 struct ifnet *srcifp;
207 struct ipqhead *head;
208 int i, hlen, next, tmpmax;
209 u_int8_t ecn, ecn0;
210 uint32_t hash, hashkey[3];
211 #ifdef RSS
212 uint32_t rss_hash, rss_type;
213 #endif
214
215 /*
216 * If no reassembling or maxfragsperpacket are 0,
217 * never accept fragments.
218 * Also, drop packet if it would exceed the maximum
219 * number of fragments.
220 */
221 tmpmax = maxfrags;
222 if (V_noreass == 1 || V_maxfragsperpacket == 0 ||
223 (tmpmax >= 0 && atomic_load_int(&nfrags) >= (u_int)tmpmax)) {
224 IPSTAT_INC(ips_fragments);
225 IPSTAT_INC(ips_fragdropped);
226 m_freem(m);
227 return (NULL);
228 }
229
230 ip = mtod(m, struct ip *);
231 hlen = ip->ip_hl << 2;
232
233 /*
234 * Adjust ip_len to not reflect header,
235 * convert offset of this to bytes.
236 */
237 ip->ip_len = htons(ntohs(ip->ip_len) - hlen);
238 /*
239 * Make sure that fragments have a data length
240 * that's a non-zero multiple of 8 bytes, unless
241 * this is the last fragment.
242 */
243 if (ip->ip_len == htons(0) ||
244 ((ip->ip_off & htons(IP_MF)) && (ntohs(ip->ip_len) & 0x7) != 0)) {
245 IPSTAT_INC(ips_toosmall); /* XXX */
246 IPSTAT_INC(ips_fragdropped);
247 m_freem(m);
248 return (NULL);
249 }
250 if (ip->ip_off & htons(IP_MF))
251 m->m_flags |= M_IP_FRAG;
252 else
253 m->m_flags &= ~M_IP_FRAG;
254 ip->ip_off = htons(ntohs(ip->ip_off) << 3);
255
256 /*
257 * Make sure the fragment lies within a packet of valid size.
258 */
259 if (ntohs(ip->ip_len) + ntohs(ip->ip_off) > IP_MAXPACKET) {
260 IPSTAT_INC(ips_toolong);
261 IPSTAT_INC(ips_fragdropped);
262 m_freem(m);
263 return (NULL);
264 }
265
266 /*
267 * Store receive network interface pointer for later.
268 */
269 srcifp = m->m_pkthdr.rcvif;
270
271 /*
272 * Attempt reassembly; if it succeeds, proceed.
273 * ip_reass() will return a different mbuf.
274 */
275 IPSTAT_INC(ips_fragments);
276 m->m_pkthdr.PH_loc.ptr = ip;
277
278 /*
279 * Presence of header sizes in mbufs
280 * would confuse code below.
281 */
282 m->m_data += hlen;
283 m->m_len -= hlen;
284
285 hashkey[0] = ip->ip_src.s_addr;
286 hashkey[1] = ip->ip_dst.s_addr;
287 hashkey[2] = (uint32_t)ip->ip_p << 16;
288 hashkey[2] += ip->ip_id;
289 hash = jenkins_hash32(hashkey, nitems(hashkey), V_ipq_hashseed);
290 hash &= IPREASS_HMASK;
291 head = &V_ipq[hash].head;
292 IPQ_LOCK(hash);
293
294 /*
295 * Look for queue of fragments
296 * of this datagram.
297 */
298 TAILQ_FOREACH(fp, head, ipq_list)
299 if (ip->ip_id == fp->ipq_id &&
300 ip->ip_src.s_addr == fp->ipq_src.s_addr &&
301 ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
302 #ifdef MAC
303 mac_ipq_match(m, fp) &&
304 #endif
305 ip->ip_p == fp->ipq_p)
306 break;
307 /*
308 * If first fragment to arrive, create a reassembly queue.
309 */
310 if (fp == NULL) {
311 if (V_ipq[hash].count < V_ipreass_maxbucketsize)
312 fp = uma_zalloc(V_ipq_zone, M_NOWAIT);
313 if (fp == NULL)
314 fp = ipq_reuse(hash);
315 if (fp == NULL)
316 goto dropfrag;
317 #ifdef MAC
318 if (mac_ipq_init(fp, M_NOWAIT) != 0) {
319 uma_zfree(V_ipq_zone, fp);
320 fp = NULL;
321 goto dropfrag;
322 }
323 mac_ipq_create(m, fp);
324 #endif
325 TAILQ_INSERT_HEAD(head, fp, ipq_list);
326 V_ipq[hash].count++;
327 fp->ipq_nfrags = 1;
328 atomic_add_int(&nfrags, 1);
329 fp->ipq_expire = time_uptime + V_ipfragttl;
330 fp->ipq_p = ip->ip_p;
331 fp->ipq_id = ip->ip_id;
332 fp->ipq_src = ip->ip_src;
333 fp->ipq_dst = ip->ip_dst;
334 fp->ipq_frags = m;
335 if (m->m_flags & M_IP_FRAG)
336 fp->ipq_maxoff = -1;
337 else
338 fp->ipq_maxoff = ntohs(ip->ip_off) + ntohs(ip->ip_len);
339 m->m_nextpkt = NULL;
340 if (fp == TAILQ_LAST(head, ipqhead))
341 callout_reset_sbt(&V_ipq[hash].timer,
342 SBT_1S * V_ipfragttl, SBT_1S, ipreass_callout,
343 &V_ipq[hash], 0);
344 else
345 MPASS(callout_active(&V_ipq[hash].timer));
346 goto done;
347 } else {
348 /*
349 * If we already saw the last fragment, make sure
350 * this fragment's offset looks sane. Otherwise, if
351 * this is the last fragment, record its endpoint.
352 */
353 if (fp->ipq_maxoff > 0) {
354 i = ntohs(ip->ip_off) + ntohs(ip->ip_len);
355 if (((m->m_flags & M_IP_FRAG) && i >= fp->ipq_maxoff) ||
356 ((m->m_flags & M_IP_FRAG) == 0 &&
357 i != fp->ipq_maxoff)) {
358 fp = NULL;
359 goto dropfrag;
360 }
361 } else if ((m->m_flags & M_IP_FRAG) == 0)
362 fp->ipq_maxoff = ntohs(ip->ip_off) + ntohs(ip->ip_len);
363 fp->ipq_nfrags++;
364 atomic_add_int(&nfrags, 1);
365 #ifdef MAC
366 mac_ipq_update(m, fp);
367 #endif
368 }
369
370 #define GETIP(m) ((struct ip*)((m)->m_pkthdr.PH_loc.ptr))
371
372 /*
373 * Handle ECN by comparing this segment with the first one;
374 * if CE is set, do not lose CE.
375 * drop if CE and not-ECT are mixed for the same packet.
376 */
377 ecn = ip->ip_tos & IPTOS_ECN_MASK;
378 ecn0 = GETIP(fp->ipq_frags)->ip_tos & IPTOS_ECN_MASK;
379 if (ecn == IPTOS_ECN_CE) {
380 if (ecn0 == IPTOS_ECN_NOTECT)
381 goto dropfrag;
382 if (ecn0 != IPTOS_ECN_CE)
383 GETIP(fp->ipq_frags)->ip_tos |= IPTOS_ECN_CE;
384 }
385 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT)
386 goto dropfrag;
387
388 /*
389 * Find a segment which begins after this one does.
390 */
391 for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt)
392 if (ntohs(GETIP(q)->ip_off) > ntohs(ip->ip_off))
393 break;
394
395 /*
396 * If there is a preceding segment, it may provide some of
397 * our data already. If so, drop the data from the incoming
398 * segment. If it provides all of our data, drop us, otherwise
399 * stick new segment in the proper place.
400 *
401 * If some of the data is dropped from the preceding
402 * segment, then it's checksum is invalidated.
403 */
404 if (p) {
405 i = ntohs(GETIP(p)->ip_off) + ntohs(GETIP(p)->ip_len) -
406 ntohs(ip->ip_off);
407 if (i > 0) {
408 if (i >= ntohs(ip->ip_len))
409 goto dropfrag;
410 m_adj(m, i);
411 m->m_pkthdr.csum_flags = 0;
412 ip->ip_off = htons(ntohs(ip->ip_off) + i);
413 ip->ip_len = htons(ntohs(ip->ip_len) - i);
414 }
415 m->m_nextpkt = p->m_nextpkt;
416 p->m_nextpkt = m;
417 } else {
418 m->m_nextpkt = fp->ipq_frags;
419 fp->ipq_frags = m;
420 }
421
422 /*
423 * While we overlap succeeding segments trim them or,
424 * if they are completely covered, dequeue them.
425 */
426 for (; q != NULL && ntohs(ip->ip_off) + ntohs(ip->ip_len) >
427 ntohs(GETIP(q)->ip_off); q = nq) {
428 i = (ntohs(ip->ip_off) + ntohs(ip->ip_len)) -
429 ntohs(GETIP(q)->ip_off);
430 if (i < ntohs(GETIP(q)->ip_len)) {
431 GETIP(q)->ip_len = htons(ntohs(GETIP(q)->ip_len) - i);
432 GETIP(q)->ip_off = htons(ntohs(GETIP(q)->ip_off) + i);
433 m_adj(q, i);
434 q->m_pkthdr.csum_flags = 0;
435 break;
436 }
437 nq = q->m_nextpkt;
438 m->m_nextpkt = nq;
439 IPSTAT_INC(ips_fragdropped);
440 fp->ipq_nfrags--;
441 atomic_subtract_int(&nfrags, 1);
442 m_freem(q);
443 }
444
445 /*
446 * Check for complete reassembly and perform frag per packet
447 * limiting.
448 *
449 * Frag limiting is performed here so that the nth frag has
450 * a chance to complete the packet before we drop the packet.
451 * As a result, n+1 frags are actually allowed per packet, but
452 * only n will ever be stored. (n = maxfragsperpacket.)
453 *
454 */
455 next = 0;
456 for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) {
457 if (ntohs(GETIP(q)->ip_off) != next) {
458 if (fp->ipq_nfrags > V_maxfragsperpacket)
459 ipq_drop(&V_ipq[hash], fp);
460 goto done;
461 }
462 next += ntohs(GETIP(q)->ip_len);
463 }
464 /* Make sure the last packet didn't have the IP_MF flag */
465 if (p->m_flags & M_IP_FRAG) {
466 if (fp->ipq_nfrags > V_maxfragsperpacket)
467 ipq_drop(&V_ipq[hash], fp);
468 goto done;
469 }
470
471 /*
472 * Reassembly is complete. Make sure the packet is a sane size.
473 */
474 q = fp->ipq_frags;
475 ip = GETIP(q);
476 if (next + (ip->ip_hl << 2) > IP_MAXPACKET) {
477 IPSTAT_INC(ips_toolong);
478 ipq_drop(&V_ipq[hash], fp);
479 goto done;
480 }
481
482 /*
483 * Concatenate fragments.
484 */
485 m = q;
486 t = m->m_next;
487 m->m_next = NULL;
488 m_cat(m, t);
489 nq = q->m_nextpkt;
490 q->m_nextpkt = NULL;
491 for (q = nq; q != NULL; q = nq) {
492 nq = q->m_nextpkt;
493 q->m_nextpkt = NULL;
494 m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags;
495 m->m_pkthdr.csum_data += q->m_pkthdr.csum_data;
496 m_demote_pkthdr(q);
497 m_cat(m, q);
498 }
499 /*
500 * In order to do checksumming faster we do 'end-around carry' here
501 * (and not in for{} loop), though it implies we are not going to
502 * reassemble more than 64k fragments.
503 */
504 while (m->m_pkthdr.csum_data & 0xffff0000)
505 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) +
506 (m->m_pkthdr.csum_data >> 16);
507 atomic_subtract_int(&nfrags, fp->ipq_nfrags);
508 #ifdef MAC
509 mac_ipq_reassemble(fp, m);
510 mac_ipq_destroy(fp);
511 #endif
512
513 /*
514 * Create header for new ip packet by modifying header of first
515 * packet; dequeue and discard fragment reassembly header.
516 * Make header visible.
517 */
518 ip->ip_len = htons((ip->ip_hl << 2) + next);
519 ip->ip_src = fp->ipq_src;
520 ip->ip_dst = fp->ipq_dst;
521 TAILQ_REMOVE(head, fp, ipq_list);
522 V_ipq[hash].count--;
523 uma_zfree(V_ipq_zone, fp);
524 m->m_len += (ip->ip_hl << 2);
525 m->m_data -= (ip->ip_hl << 2);
526 /* some debugging cruft by sklower, below, will go away soon */
527 if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
528 m_fixhdr(m);
529 /* set valid receive interface pointer */
530 m->m_pkthdr.rcvif = srcifp;
531 }
532 IPSTAT_INC(ips_reassembled);
533 ipreass_reschedule(&V_ipq[hash]);
534 IPQ_UNLOCK(hash);
535
536 #ifdef RSS
537 /*
538 * Query the RSS layer for the flowid / flowtype for the
539 * mbuf payload.
540 *
541 * For now, just assume we have to calculate a new one.
542 * Later on we should check to see if the assigned flowid matches
543 * what RSS wants for the given IP protocol and if so, just keep it.
544 *
545 * We then queue into the relevant netisr so it can be dispatched
546 * to the correct CPU.
547 *
548 * Note - this may return 1, which means the flowid in the mbuf
549 * is correct for the configured RSS hash types and can be used.
550 */
551 if (rss_mbuf_software_hash_v4(m, 0, &rss_hash, &rss_type) == 0) {
552 m->m_pkthdr.flowid = rss_hash;
553 M_HASHTYPE_SET(m, rss_type);
554 }
555
556 /*
557 * Queue/dispatch for reprocessing.
558 *
559 * Note: this is much slower than just handling the frame in the
560 * current receive context. It's likely worth investigating
561 * why this is.
562 */
563 netisr_dispatch(NETISR_IP_DIRECT, m);
564 return (NULL);
565 #endif
566
567 /* Handle in-line */
568 return (m);
569
570 dropfrag:
571 IPSTAT_INC(ips_fragdropped);
572 if (fp != NULL) {
573 fp->ipq_nfrags--;
574 atomic_subtract_int(&nfrags, 1);
575 }
576 m_freem(m);
577 done:
578 IPQ_UNLOCK(hash);
579 return (NULL);
580
581 #undef GETIP
582 }
583
584 /*
585 * Timer expired on a bucket.
586 * There should be at least one ipq to be timed out.
587 */
588 static void
ipreass_callout(void * arg)589 ipreass_callout(void *arg)
590 {
591 struct ipqbucket *bucket = arg;
592 struct ipq *fp;
593
594 IPQ_BUCKET_LOCK_ASSERT(bucket);
595 MPASS(atomic_load_int(&nfrags) > 0);
596
597 CURVNET_SET(bucket->vnet);
598 fp = TAILQ_LAST(&bucket->head, ipqhead);
599 KASSERT(fp != NULL && fp->ipq_expire <= time_uptime,
600 ("%s: stray callout on bucket %p, %ju < %ju", __func__, bucket,
601 fp ? (uintmax_t)fp->ipq_expire : 0, (uintmax_t)time_uptime));
602
603 while (fp != NULL && fp->ipq_expire <= time_uptime) {
604 ipq_timeout(bucket, fp);
605 fp = TAILQ_LAST(&bucket->head, ipqhead);
606 }
607 ipreass_reschedule(bucket);
608 CURVNET_RESTORE();
609 }
610
611 static void
ipreass_reschedule(struct ipqbucket * bucket)612 ipreass_reschedule(struct ipqbucket *bucket)
613 {
614 struct ipq *fp;
615
616 IPQ_BUCKET_LOCK_ASSERT(bucket);
617
618 if ((fp = TAILQ_LAST(&bucket->head, ipqhead)) != NULL) {
619 time_t t;
620
621 /* Protect against time_uptime tick. */
622 t = fp->ipq_expire - time_uptime;
623 t = (t > 0) ? t : 1;
624 callout_reset_sbt(&bucket->timer, SBT_1S * t, SBT_1S,
625 ipreass_callout, bucket, 0);
626 } else
627 callout_stop(&bucket->timer);
628 }
629
630 static void
ipreass_drain_vnet(void)631 ipreass_drain_vnet(void)
632 {
633 u_int dropped = 0;
634
635 for (int i = 0; i < V_ipq_hashsize; i++) {
636 bool resched;
637
638 IPQ_LOCK(i);
639 resched = !TAILQ_EMPTY(&V_ipq[i].head);
640 while(!TAILQ_EMPTY(&V_ipq[i].head)) {
641 struct ipq *fp = TAILQ_FIRST(&V_ipq[i].head);
642
643 dropped += fp->ipq_nfrags;
644 ipq_free(&V_ipq[i], fp);
645 }
646 if (resched)
647 ipreass_reschedule(&V_ipq[i]);
648 KASSERT(V_ipq[i].count == 0,
649 ("%s: V_ipq[%d] count %d (V_ipq=%p)", __func__, i,
650 V_ipq[i].count, V_ipq));
651 IPQ_UNLOCK(i);
652 }
653 IPSTAT_ADD(ips_fragdropped, dropped);
654 }
655
656 /*
657 * Drain off all datagram fragments.
658 */
659 static void
ipreass_drain(void)660 ipreass_drain(void)
661 {
662 VNET_ITERATOR_DECL(vnet_iter);
663
664 VNET_LIST_RLOCK();
665 VNET_FOREACH(vnet_iter) {
666 CURVNET_SET(vnet_iter);
667 ipreass_drain_vnet();
668 CURVNET_RESTORE();
669 }
670 VNET_LIST_RUNLOCK();
671 }
672
673
674 /*
675 * Initialize IP reassembly structures.
676 */
677 MALLOC_DEFINE(M_IPREASS_HASH, "IP reass", "IP packet reassembly hash headers");
678 void
ipreass_vnet_init(void)679 ipreass_vnet_init(void)
680 {
681 int max;
682
683 V_ipq_hashsize = IPREASS_NHASH;
684 TUNABLE_INT_FETCH("net.inet.ip.reass_hashsize", &V_ipq_hashsize);
685 V_ipq = malloc(sizeof(struct ipqbucket) * V_ipq_hashsize,
686 M_IPREASS_HASH, M_WAITOK);
687
688 for (int i = 0; i < V_ipq_hashsize; i++) {
689 TAILQ_INIT(&V_ipq[i].head);
690 mtx_init(&V_ipq[i].lock, "IP reassembly", NULL,
691 MTX_DEF | MTX_DUPOK | MTX_NEW);
692 callout_init_mtx(&V_ipq[i].timer, &V_ipq[i].lock, 0);
693 V_ipq[i].count = 0;
694 #ifdef VIMAGE
695 V_ipq[i].vnet = curvnet;
696 #endif
697 }
698 V_ipq_hashseed = arc4random();
699 V_maxfragsperpacket = 16;
700 V_ipq_zone = uma_zcreate("ipq", sizeof(struct ipq), NULL, NULL, NULL,
701 NULL, UMA_ALIGN_PTR, 0);
702 max = IP_MAXFRAGPACKETS;
703 max = uma_zone_set_max(V_ipq_zone, max);
704 V_ipreass_maxbucketsize = imax(max / (V_ipq_hashsize / 2), 1);
705 }
706
707 void
ipreass_init(void)708 ipreass_init(void)
709 {
710
711 maxfrags = IP_MAXFRAGS;
712 EVENTHANDLER_REGISTER(nmbclusters_change, ipreass_zone_change,
713 NULL, EVENTHANDLER_PRI_ANY);
714 EVENTHANDLER_REGISTER(vm_lowmem, ipreass_drain, NULL,
715 LOWMEM_PRI_DEFAULT);
716 EVENTHANDLER_REGISTER(mbuf_lowmem, ipreass_drain, NULL,
717 LOWMEM_PRI_DEFAULT);
718 }
719
720 /*
721 * Drain off all datagram fragments belonging to
722 * the given network interface.
723 */
724 static void
ipreass_cleanup(void * arg __unused,struct ifnet * ifp)725 ipreass_cleanup(void *arg __unused, struct ifnet *ifp)
726 {
727 struct ipq *fp, *temp;
728 struct mbuf *m;
729 int i;
730
731 KASSERT(ifp != NULL, ("%s: ifp is NULL", __func__));
732
733 CURVNET_SET_QUIET(ifp->if_vnet);
734
735 /*
736 * Skip processing if IPv4 reassembly is not initialised or
737 * torn down by ipreass_destroy().
738 */
739 if (V_ipq_zone == NULL) {
740 CURVNET_RESTORE();
741 return;
742 }
743
744 for (i = 0; i < V_ipq_hashsize; i++) {
745 IPQ_LOCK(i);
746 /* Scan fragment list. */
747 TAILQ_FOREACH_SAFE(fp, &V_ipq[i].head, ipq_list, temp) {
748 for (m = fp->ipq_frags; m != NULL; m = m->m_nextpkt) {
749 /* clear no longer valid rcvif pointer */
750 if (m->m_pkthdr.rcvif == ifp)
751 m->m_pkthdr.rcvif = NULL;
752 }
753 }
754 IPQ_UNLOCK(i);
755 }
756 CURVNET_RESTORE();
757 }
758 EVENTHANDLER_DEFINE(ifnet_departure_event, ipreass_cleanup, NULL, 0);
759
760 #ifdef VIMAGE
761 /*
762 * Destroy IP reassembly structures.
763 */
764 void
ipreass_destroy(void)765 ipreass_destroy(void)
766 {
767
768 ipreass_drain_vnet();
769 uma_zdestroy(V_ipq_zone);
770 V_ipq_zone = NULL;
771 for (int i = 0; i < V_ipq_hashsize; i++)
772 mtx_destroy(&V_ipq[i].lock);
773 free(V_ipq, M_IPREASS_HASH);
774 }
775 #endif
776
777 /*
778 * After maxnipq has been updated, propagate the change to UMA. The UMA zone
779 * max has slightly different semantics than the sysctl, for historical
780 * reasons.
781 */
782 static void
ipreass_drain_tomax(void)783 ipreass_drain_tomax(void)
784 {
785 struct ipq *fp;
786 int target;
787
788 /*
789 * Make sure each bucket is under the new limit. If
790 * necessary, drop enough of the oldest elements from
791 * each bucket to get under the new limit.
792 */
793 for (int i = 0; i < V_ipq_hashsize; i++) {
794 IPQ_LOCK(i);
795 while (V_ipq[i].count > V_ipreass_maxbucketsize &&
796 (fp = TAILQ_LAST(&V_ipq[i].head, ipqhead)) != NULL)
797 ipq_timeout(&V_ipq[i], fp);
798 ipreass_reschedule(&V_ipq[i]);
799 IPQ_UNLOCK(i);
800 }
801
802 /*
803 * If we are over the maximum number of fragments,
804 * drain off enough to get down to the new limit,
805 * stripping off last elements on queues. Every
806 * run we strip the oldest element from each bucket.
807 */
808 target = uma_zone_get_max(V_ipq_zone);
809 while (uma_zone_get_cur(V_ipq_zone) > target) {
810 for (int i = 0; i < V_ipq_hashsize; i++) {
811 IPQ_LOCK(i);
812 fp = TAILQ_LAST(&V_ipq[i].head, ipqhead);
813 if (fp != NULL) {
814 ipq_timeout(&V_ipq[i], fp);
815 ipreass_reschedule(&V_ipq[i]);
816 }
817 IPQ_UNLOCK(i);
818 }
819 }
820 }
821
822 static void
ipreass_zone_change(void * tag)823 ipreass_zone_change(void *tag)
824 {
825 VNET_ITERATOR_DECL(vnet_iter);
826 int max;
827
828 maxfrags = IP_MAXFRAGS;
829 max = IP_MAXFRAGPACKETS;
830 VNET_LIST_RLOCK_NOSLEEP();
831 VNET_FOREACH(vnet_iter) {
832 CURVNET_SET(vnet_iter);
833 max = uma_zone_set_max(V_ipq_zone, max);
834 V_ipreass_maxbucketsize = imax(max / (V_ipq_hashsize / 2), 1);
835 ipreass_drain_tomax();
836 CURVNET_RESTORE();
837 }
838 VNET_LIST_RUNLOCK_NOSLEEP();
839 }
840
841 /*
842 * Change the limit on the UMA zone, or disable the fragment allocation
843 * at all. Since 0 and -1 is a special values here, we need our own handler,
844 * instead of sysctl_handle_uma_zone_max().
845 */
846 static int
sysctl_maxfragpackets(SYSCTL_HANDLER_ARGS)847 sysctl_maxfragpackets(SYSCTL_HANDLER_ARGS)
848 {
849 int error, max;
850
851 if (V_noreass == 0) {
852 max = uma_zone_get_max(V_ipq_zone);
853 if (max == 0)
854 max = -1;
855 } else
856 max = 0;
857 error = sysctl_handle_int(oidp, &max, 0, req);
858 if (error || !req->newptr)
859 return (error);
860 if (max > 0) {
861 /*
862 * XXXRW: Might be a good idea to sanity check the argument
863 * and place an extreme upper bound.
864 */
865 max = uma_zone_set_max(V_ipq_zone, max);
866 V_ipreass_maxbucketsize = imax(max / (V_ipq_hashsize / 2), 1);
867 ipreass_drain_tomax();
868 V_noreass = 0;
869 } else if (max == 0) {
870 V_noreass = 1;
871 ipreass_drain();
872 } else if (max == -1) {
873 V_noreass = 0;
874 uma_zone_set_max(V_ipq_zone, 0);
875 V_ipreass_maxbucketsize = INT_MAX;
876 } else
877 return (EINVAL);
878 return (0);
879 }
880
881 /*
882 * Seek for old fragment queue header that can be reused. Try to
883 * reuse a header from currently locked hash bucket.
884 */
885 static struct ipq *
ipq_reuse(int start)886 ipq_reuse(int start)
887 {
888 struct ipq *fp;
889 int bucket, i;
890
891 IPQ_LOCK_ASSERT(start);
892
893 for (i = 0; i < V_ipq_hashsize; i++) {
894 bucket = (start + i) % V_ipq_hashsize;
895 if (bucket != start && IPQ_TRYLOCK(bucket) == 0)
896 continue;
897 fp = TAILQ_LAST(&V_ipq[bucket].head, ipqhead);
898 if (fp) {
899 struct mbuf *m;
900
901 IPSTAT_ADD(ips_fragtimeout, fp->ipq_nfrags);
902 atomic_subtract_int(&nfrags, fp->ipq_nfrags);
903 while (fp->ipq_frags) {
904 m = fp->ipq_frags;
905 fp->ipq_frags = m->m_nextpkt;
906 m_freem(m);
907 }
908 TAILQ_REMOVE(&V_ipq[bucket].head, fp, ipq_list);
909 V_ipq[bucket].count--;
910 ipreass_reschedule(&V_ipq[bucket]);
911 if (bucket != start)
912 IPQ_UNLOCK(bucket);
913 break;
914 }
915 if (bucket != start)
916 IPQ_UNLOCK(bucket);
917 }
918 IPQ_LOCK_ASSERT(start);
919 return (fp);
920 }
921
922 /*
923 * Free a fragment reassembly header and all associated datagrams.
924 */
925 static void
ipq_free(struct ipqbucket * bucket,struct ipq * fp)926 ipq_free(struct ipqbucket *bucket, struct ipq *fp)
927 {
928 struct mbuf *q;
929
930 atomic_subtract_int(&nfrags, fp->ipq_nfrags);
931 while (fp->ipq_frags) {
932 q = fp->ipq_frags;
933 fp->ipq_frags = q->m_nextpkt;
934 m_freem(q);
935 }
936 TAILQ_REMOVE(&bucket->head, fp, ipq_list);
937 bucket->count--;
938 uma_zfree(V_ipq_zone, fp);
939 }
940
941 /*
942 * Get or set the maximum number of reassembly queues per bucket.
943 */
944 static int
sysctl_maxfragbucketsize(SYSCTL_HANDLER_ARGS)945 sysctl_maxfragbucketsize(SYSCTL_HANDLER_ARGS)
946 {
947 int error, max;
948
949 max = V_ipreass_maxbucketsize;
950 error = sysctl_handle_int(oidp, &max, 0, req);
951 if (error || !req->newptr)
952 return (error);
953 if (max <= 0)
954 return (EINVAL);
955 V_ipreass_maxbucketsize = max;
956 ipreass_drain_tomax();
957 return (0);
958 }
959
960 /*
961 * Get or set the IP fragment time to live.
962 */
963 static int
sysctl_fragttl(SYSCTL_HANDLER_ARGS)964 sysctl_fragttl(SYSCTL_HANDLER_ARGS)
965 {
966 u_int ttl;
967 int error;
968
969 ttl = V_ipfragttl;
970 error = sysctl_handle_int(oidp, &ttl, 0, req);
971 if (error || !req->newptr)
972 return (error);
973
974 if (ttl < 1 || ttl > MAXTTL)
975 return (EINVAL);
976
977 atomic_store_int(&V_ipfragttl, ttl);
978 return (0);
979 }
980