FreeBSD/Linux Kernel Cross Reference
sys/netinet6/frag6.c
1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
5 * All rights reserved.
6 * Copyright (c) 2019 Netflix, Inc.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the project nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * $KAME: frag6.c,v 1.33 2002/01/07 11:34:48 kjc Exp $
33 */
34
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
37
38 #include "opt_rss.h"
39
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/domain.h>
43 #include <sys/eventhandler.h>
44 #include <sys/hash.h>
45 #include <sys/kernel.h>
46 #include <sys/malloc.h>
47 #include <sys/mbuf.h>
48 #include <sys/protosw.h>
49 #include <sys/queue.h>
50 #include <sys/socket.h>
51 #include <sys/sysctl.h>
52 #include <sys/syslog.h>
53
54 #include <net/if.h>
55 #include <net/if_var.h>
56 #include <net/netisr.h>
57 #include <net/route.h>
58 #include <net/vnet.h>
59
60 #include <netinet/in.h>
61 #include <netinet/in_var.h>
62 #include <netinet/ip6.h>
63 #include <netinet6/ip6_var.h>
64 #include <netinet/icmp6.h>
65 #include <netinet/in_systm.h> /* For ECN definitions. */
66 #include <netinet/ip.h> /* For ECN definitions. */
67
68 #ifdef MAC
69 #include <security/mac/mac_framework.h>
70 #endif
71
72 /*
73 * A "big picture" of how IPv6 fragment queues are all linked together.
74 *
75 * struct ip6qbucket ip6qb[...]; hashed buckets
76 * ||||||||
77 * |
78 * +--- TAILQ(struct ip6q, packets) *q6; tailq entries holding
79 * |||||||| fragmented packets
80 * | (1 per original packet)
81 * |
82 * +--- TAILQ(struct ip6asfrag, ip6q_frags) *af6; tailq entries of IPv6
83 * | *ip6af;fragment packets
84 * | for one original packet
85 * + *mbuf
86 */
87
88 /* Reassembly headers are stored in hash buckets. */
89 #define IP6REASS_NHASH_LOG2 10
90 #define IP6REASS_NHASH (1 << IP6REASS_NHASH_LOG2)
91 #define IP6REASS_HMASK (IP6REASS_NHASH - 1)
92
93 TAILQ_HEAD(ip6qhead, ip6q);
94 struct ip6qbucket {
95 struct ip6qhead packets;
96 struct mtx lock;
97 int count;
98 };
99
100 struct ip6asfrag {
101 TAILQ_ENTRY(ip6asfrag) ip6af_tq;
102 struct mbuf *ip6af_m;
103 int ip6af_offset; /* Offset in ip6af_m to next header. */
104 int ip6af_frglen; /* Fragmentable part length. */
105 int ip6af_off; /* Fragment offset. */
106 bool ip6af_mff; /* More fragment bit in frag off. */
107 };
108
109 static MALLOC_DEFINE(M_FRAG6, "frag6", "IPv6 fragment reassembly header");
110
111 #ifdef VIMAGE
112 /* A flag to indicate if IPv6 fragmentation is initialized. */
113 VNET_DEFINE_STATIC(bool, frag6_on);
114 #define V_frag6_on VNET(frag6_on)
115 #endif
116
117 /* System wide (global) maximum and count of packets in reassembly queues. */
118 static int ip6_maxfrags;
119 static u_int __exclusive_cache_line frag6_nfrags;
120
121 /* Maximum and current packets in per-VNET reassembly queue. */
122 VNET_DEFINE_STATIC(int, ip6_maxfragpackets);
123 VNET_DEFINE_STATIC(volatile u_int, frag6_nfragpackets);
124 #define V_ip6_maxfragpackets VNET(ip6_maxfragpackets)
125 #define V_frag6_nfragpackets VNET(frag6_nfragpackets)
126
127 /* Maximum per-VNET reassembly queues per bucket and fragments per packet. */
128 VNET_DEFINE_STATIC(int, ip6_maxfragbucketsize);
129 VNET_DEFINE_STATIC(int, ip6_maxfragsperpacket);
130 #define V_ip6_maxfragbucketsize VNET(ip6_maxfragbucketsize)
131 #define V_ip6_maxfragsperpacket VNET(ip6_maxfragsperpacket)
132
133 /* Per-VNET reassembly queue buckets. */
134 VNET_DEFINE_STATIC(struct ip6qbucket, ip6qb[IP6REASS_NHASH]);
135 VNET_DEFINE_STATIC(uint32_t, ip6qb_hashseed);
136 #define V_ip6qb VNET(ip6qb)
137 #define V_ip6qb_hashseed VNET(ip6qb_hashseed)
138
139 #define IP6QB_LOCK(_b) mtx_lock(&V_ip6qb[(_b)].lock)
140 #define IP6QB_TRYLOCK(_b) mtx_trylock(&V_ip6qb[(_b)].lock)
141 #define IP6QB_LOCK_ASSERT(_b) mtx_assert(&V_ip6qb[(_b)].lock, MA_OWNED)
142 #define IP6QB_UNLOCK(_b) mtx_unlock(&V_ip6qb[(_b)].lock)
143 #define IP6QB_HEAD(_b) (&V_ip6qb[(_b)].packets)
144
145 /*
146 * By default, limit the number of IP6 fragments across all reassembly
147 * queues to 1/32 of the total number of mbuf clusters.
148 *
149 * Limit the total number of reassembly queues per VNET to the
150 * IP6 fragment limit, but ensure the limit will not allow any bucket
151 * to grow above 100 items. (The bucket limit is
152 * IP_MAXFRAGPACKETS / (IPREASS_NHASH / 2), so the 50 is the correct
153 * multiplier to reach a 100-item limit.)
154 * The 100-item limit was chosen as brief testing seems to show that
155 * this produces "reasonable" performance on some subset of systems
156 * under DoS attack.
157 */
158 #define IP6_MAXFRAGS (nmbclusters / 32)
159 #define IP6_MAXFRAGPACKETS (imin(IP6_MAXFRAGS, IP6REASS_NHASH * 50))
160
161
162 /*
163 * Sysctls and helper function.
164 */
165 SYSCTL_DECL(_net_inet6_ip6);
166
167 SYSCTL_UINT(_net_inet6_ip6, OID_AUTO, frag6_nfrags,
168 CTLFLAG_RD, &frag6_nfrags, 0,
169 "Global number of IPv6 fragments across all reassembly queues.");
170
171 static void
172 frag6_set_bucketsize(void)
173 {
174 int i;
175
176 if ((i = V_ip6_maxfragpackets) > 0)
177 V_ip6_maxfragbucketsize = imax(i / (IP6REASS_NHASH / 2), 1);
178 }
179
180 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGS, maxfrags,
181 CTLFLAG_RW, &ip6_maxfrags, 0,
182 "Maximum allowed number of outstanding IPv6 packet fragments. "
183 "A value of 0 means no fragmented packets will be accepted, while "
184 "a value of -1 means no limit");
185
186 static int
187 sysctl_ip6_maxfragpackets(SYSCTL_HANDLER_ARGS)
188 {
189 int error, val;
190
191 val = V_ip6_maxfragpackets;
192 error = sysctl_handle_int(oidp, &val, 0, req);
193 if (error != 0 || !req->newptr)
194 return (error);
195 V_ip6_maxfragpackets = val;
196 frag6_set_bucketsize();
197 return (0);
198 }
199 SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_MAXFRAGPACKETS, maxfragpackets,
200 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW, NULL, 0,
201 sysctl_ip6_maxfragpackets, "I",
202 "Default maximum number of outstanding fragmented IPv6 packets. "
203 "A value of 0 means no fragmented packets will be accepted, while a "
204 "a value of -1 means no limit");
205 SYSCTL_UINT(_net_inet6_ip6, OID_AUTO, frag6_nfragpackets,
206 CTLFLAG_VNET | CTLFLAG_RD,
207 __DEVOLATILE(u_int *, &VNET_NAME(frag6_nfragpackets)), 0,
208 "Per-VNET number of IPv6 fragments across all reassembly queues.");
209 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGSPERPACKET, maxfragsperpacket,
210 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_maxfragsperpacket), 0,
211 "Maximum allowed number of fragments per packet");
212 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGBUCKETSIZE, maxfragbucketsize,
213 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_maxfragbucketsize), 0,
214 "Maximum number of reassembly queues per hash bucket");
215
216
217 /*
218 * Remove the IPv6 fragmentation header from the mbuf.
219 */
220 int
221 ip6_deletefraghdr(struct mbuf *m, int offset, int wait __unused)
222 {
223 struct ip6_hdr *ip6;
224
225 KASSERT(m->m_len >= offset + sizeof(struct ip6_frag),
226 ("%s: ext headers not contigous in mbuf %p m_len %d >= "
227 "offset %d + %zu\n", __func__, m, m->m_len, offset,
228 sizeof(struct ip6_frag)));
229
230 /* Delete frag6 header. */
231 ip6 = mtod(m, struct ip6_hdr *);
232 bcopy(ip6, (char *)ip6 + sizeof(struct ip6_frag), offset);
233 m->m_data += sizeof(struct ip6_frag);
234 m->m_len -= sizeof(struct ip6_frag);
235 m->m_flags |= M_FRAGMENTED;
236
237 return (0);
238 }
239
240 /*
241 * Free a fragment reassembly header and all associated datagrams.
242 */
243 static void
244 frag6_freef(struct ip6q *q6, uint32_t bucket)
245 {
246 struct ip6_hdr *ip6;
247 struct ip6asfrag *af6;
248 struct mbuf *m;
249
250 IP6QB_LOCK_ASSERT(bucket);
251
252 while ((af6 = TAILQ_FIRST(&q6->ip6q_frags)) != NULL) {
253
254 m = af6->ip6af_m;
255 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq);
256
257 /*
258 * Return ICMP time exceeded error for the 1st fragment.
259 * Just free other fragments.
260 */
261 if (af6->ip6af_off == 0 && m->m_pkthdr.rcvif != NULL) {
262
263 /* Adjust pointer. */
264 ip6 = mtod(m, struct ip6_hdr *);
265
266 /* Restore source and destination addresses. */
267 ip6->ip6_src = q6->ip6q_src;
268 ip6->ip6_dst = q6->ip6q_dst;
269
270 icmp6_error(m, ICMP6_TIME_EXCEEDED,
271 ICMP6_TIME_EXCEED_REASSEMBLY, 0);
272 } else
273 m_freem(m);
274
275 free(af6, M_FRAG6);
276 }
277
278 TAILQ_REMOVE(IP6QB_HEAD(bucket), q6, ip6q_tq);
279 V_ip6qb[bucket].count--;
280 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag);
281 #ifdef MAC
282 mac_ip6q_destroy(q6);
283 #endif
284 free(q6, M_FRAG6);
285 atomic_subtract_int(&V_frag6_nfragpackets, 1);
286 }
287
288 /*
289 * Drain off all datagram fragments belonging to
290 * the given network interface.
291 */
292 static void
293 frag6_cleanup(void *arg __unused, struct ifnet *ifp)
294 {
295 struct ip6qhead *head;
296 struct ip6q *q6;
297 struct ip6asfrag *af6;
298 uint32_t bucket;
299
300 KASSERT(ifp != NULL, ("%s: ifp is NULL", __func__));
301
302 CURVNET_SET_QUIET(ifp->if_vnet);
303 #ifdef VIMAGE
304 /*
305 * Skip processing if IPv6 reassembly is not initialised or
306 * torn down by frag6_destroy().
307 */
308 if (!V_frag6_on) {
309 CURVNET_RESTORE();
310 return;
311 }
312 #endif
313
314 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
315 IP6QB_LOCK(bucket);
316 head = IP6QB_HEAD(bucket);
317 /* Scan fragment list. */
318 TAILQ_FOREACH(q6, head, ip6q_tq) {
319 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) {
320
321 /* Clear no longer valid rcvif pointer. */
322 if (af6->ip6af_m->m_pkthdr.rcvif == ifp)
323 af6->ip6af_m->m_pkthdr.rcvif = NULL;
324 }
325 }
326 IP6QB_UNLOCK(bucket);
327 }
328 CURVNET_RESTORE();
329 }
330 EVENTHANDLER_DEFINE(ifnet_departure_event, frag6_cleanup, NULL, 0);
331
332 /*
333 * Like in RFC2460, in RFC8200, fragment and reassembly rules do not agree with
334 * each other, in terms of next header field handling in fragment header.
335 * While the sender will use the same value for all of the fragmented packets,
336 * receiver is suggested not to check for consistency.
337 *
338 * Fragment rules (p18,p19):
339 * (2) A Fragment header containing:
340 * The Next Header value that identifies the first header
341 * after the Per-Fragment headers of the original packet.
342 * -> next header field is same for all fragments
343 *
344 * Reassembly rule (p20):
345 * The Next Header field of the last header of the Per-Fragment
346 * headers is obtained from the Next Header field of the first
347 * fragment's Fragment header.
348 * -> should grab it from the first fragment only
349 *
350 * The following note also contradicts with fragment rule - no one is going to
351 * send different fragment with different next header field.
352 *
353 * Additional note (p22) [not an error]:
354 * The Next Header values in the Fragment headers of different
355 * fragments of the same original packet may differ. Only the value
356 * from the Offset zero fragment packet is used for reassembly.
357 * -> should grab it from the first fragment only
358 *
359 * There is no explicit reason given in the RFC. Historical reason maybe?
360 */
361 /*
362 * Fragment input.
363 */
364 int
365 frag6_input(struct mbuf **mp, int *offp, int proto)
366 {
367 struct mbuf *m, *t;
368 struct ip6_hdr *ip6;
369 struct ip6_frag *ip6f;
370 struct ip6qhead *head;
371 struct ip6q *q6;
372 struct ip6asfrag *af6, *ip6af, *af6tmp;
373 struct in6_ifaddr *ia6;
374 struct ifnet *dstifp, *srcifp;
375 uint32_t hashkey[(sizeof(struct in6_addr) * 2 +
376 sizeof(ip6f->ip6f_ident)) / sizeof(uint32_t)];
377 uint32_t bucket, *hashkeyp;
378 int fragoff, frgpartlen; /* Must be larger than uint16_t. */
379 int nxt, offset, plen;
380 uint8_t ecn, ecn0;
381 bool only_frag;
382 #ifdef RSS
383 struct ip6_direct_ctx *ip6dc;
384 struct m_tag *mtag;
385 #endif
386
387 m = *mp;
388 offset = *offp;
389
390 M_ASSERTPKTHDR(m);
391
392 if (m->m_len < offset + sizeof(struct ip6_frag)) {
393 m = m_pullup(m, offset + sizeof(struct ip6_frag));
394 if (m == NULL) {
395 IP6STAT_INC(ip6s_exthdrtoolong);
396 *mp = NULL;
397 return (IPPROTO_DONE);
398 }
399 }
400 ip6 = mtod(m, struct ip6_hdr *);
401
402 dstifp = NULL;
403 /* Find the destination interface of the packet. */
404 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */);
405 if (ia6 != NULL) {
406 dstifp = ia6->ia_ifp;
407 ifa_free(&ia6->ia_ifa);
408 }
409
410 /* Jumbo payload cannot contain a fragment header. */
411 if (ip6->ip6_plen == 0) {
412 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
413 in6_ifstat_inc(dstifp, ifs6_reass_fail);
414 *mp = NULL;
415 return (IPPROTO_DONE);
416 }
417
418 /*
419 * Check whether fragment packet's fragment length is a
420 * multiple of 8 octets (unless it is the last one).
421 * sizeof(struct ip6_frag) == 8
422 * sizeof(struct ip6_hdr) = 40
423 */
424 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset);
425 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
426 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
427 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
428 offsetof(struct ip6_hdr, ip6_plen));
429 in6_ifstat_inc(dstifp, ifs6_reass_fail);
430 *mp = NULL;
431 return (IPPROTO_DONE);
432 }
433
434 IP6STAT_INC(ip6s_fragments);
435 in6_ifstat_inc(dstifp, ifs6_reass_reqd);
436
437 /*
438 * Handle "atomic" fragments (offset and m bit set to 0) upfront,
439 * unrelated to any reassembly. We need to remove the frag hdr
440 * which is ugly.
441 * See RFC 6946 and section 4.5 of RFC 8200.
442 */
443 if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) {
444 IP6STAT_INC(ip6s_atomicfrags);
445 nxt = ip6f->ip6f_nxt;
446 /*
447 * Set nxt(-hdr field value) to the original value.
448 * We cannot just set ip6->ip6_nxt as there might be
449 * an unfragmentable part with extension headers and
450 * we must update the last one.
451 */
452 m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t),
453 (caddr_t)&nxt);
454 ip6->ip6_plen = htons(ntohs(ip6->ip6_plen) -
455 sizeof(struct ip6_frag));
456 if (ip6_deletefraghdr(m, offset, M_NOWAIT) != 0)
457 goto dropfrag2;
458 m->m_pkthdr.len -= sizeof(struct ip6_frag);
459 in6_ifstat_inc(dstifp, ifs6_reass_ok);
460 *mp = m;
461 return (nxt);
462 }
463
464 /* Offset now points to data portion. */
465 offset += sizeof(struct ip6_frag);
466
467 /* Get fragment length and discard 0-byte fragments. */
468 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
469 if (frgpartlen == 0) {
470 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
471 offsetof(struct ip6_hdr, ip6_plen));
472 in6_ifstat_inc(dstifp, ifs6_reass_fail);
473 IP6STAT_INC(ip6s_fragdropped);
474 *mp = NULL;
475 return (IPPROTO_DONE);
476 }
477
478 /*
479 * Enforce upper bound on number of fragments for the entire system.
480 * If maxfrag is 0, never accept fragments.
481 * If maxfrag is -1, accept all fragments without limitation.
482 */
483 if (ip6_maxfrags < 0)
484 ;
485 else if (atomic_load_int(&frag6_nfrags) >= (u_int)ip6_maxfrags)
486 goto dropfrag2;
487
488 /*
489 * Validate that a full header chain to the ULP is present in the
490 * packet containing the first fragment as per RFC RFC7112 and
491 * RFC 8200 pages 18,19:
492 * The first fragment packet is composed of:
493 * (3) Extension headers, if any, and the Upper-Layer header. These
494 * headers must be in the first fragment. ...
495 */
496 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
497 /* XXX TODO. thj has D16851 open for this. */
498 /* Send ICMPv6 4,3 in case of violation. */
499
500 /* Store receive network interface pointer for later. */
501 srcifp = m->m_pkthdr.rcvif;
502
503 /* Generate a hash value for fragment bucket selection. */
504 hashkeyp = hashkey;
505 memcpy(hashkeyp, &ip6->ip6_src, sizeof(struct in6_addr));
506 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp);
507 memcpy(hashkeyp, &ip6->ip6_dst, sizeof(struct in6_addr));
508 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp);
509 *hashkeyp = ip6f->ip6f_ident;
510 bucket = jenkins_hash32(hashkey, nitems(hashkey), V_ip6qb_hashseed);
511 bucket &= IP6REASS_HMASK;
512 IP6QB_LOCK(bucket);
513 head = IP6QB_HEAD(bucket);
514
515 TAILQ_FOREACH(q6, head, ip6q_tq)
516 if (ip6f->ip6f_ident == q6->ip6q_ident &&
517 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
518 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst)
519 #ifdef MAC
520 && mac_ip6q_match(m, q6)
521 #endif
522 )
523 break;
524
525 only_frag = false;
526 if (q6 == NULL) {
527
528 /* A first fragment to arrive creates a reassembly queue. */
529 only_frag = true;
530
531 /*
532 * Enforce upper bound on number of fragmented packets
533 * for which we attempt reassembly;
534 * If maxfragpackets is 0, never accept fragments.
535 * If maxfragpackets is -1, accept all fragments without
536 * limitation.
537 */
538 if (V_ip6_maxfragpackets < 0)
539 ;
540 else if (V_ip6qb[bucket].count >= V_ip6_maxfragbucketsize ||
541 atomic_load_int(&V_frag6_nfragpackets) >=
542 (u_int)V_ip6_maxfragpackets)
543 goto dropfrag;
544
545 /* Allocate IPv6 fragement packet queue entry. */
546 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FRAG6,
547 M_NOWAIT | M_ZERO);
548 if (q6 == NULL)
549 goto dropfrag;
550 #ifdef MAC
551 if (mac_ip6q_init(q6, M_NOWAIT) != 0) {
552 free(q6, M_FRAG6);
553 goto dropfrag;
554 }
555 mac_ip6q_create(m, q6);
556 #endif
557 atomic_add_int(&V_frag6_nfragpackets, 1);
558
559 /* ip6q_nxt will be filled afterwards, from 1st fragment. */
560 TAILQ_INIT(&q6->ip6q_frags);
561 q6->ip6q_ident = ip6f->ip6f_ident;
562 q6->ip6q_ttl = IPV6_FRAGTTL;
563 q6->ip6q_src = ip6->ip6_src;
564 q6->ip6q_dst = ip6->ip6_dst;
565 q6->ip6q_ecn =
566 (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
567 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
568
569 /* Add the fragemented packet to the bucket. */
570 TAILQ_INSERT_HEAD(head, q6, ip6q_tq);
571 V_ip6qb[bucket].count++;
572 }
573
574 /*
575 * If it is the 1st fragment, record the length of the
576 * unfragmentable part and the next header of the fragment header.
577 * Assume the first 1st fragement to arrive will be correct.
578 * We do not have any duplicate checks here yet so another packet
579 * with fragoff == 0 could come and overwrite the ip6q_unfrglen
580 * and worse, the next header, at any time.
581 */
582 if (fragoff == 0 && q6->ip6q_unfrglen == -1) {
583 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) -
584 sizeof(struct ip6_frag);
585 q6->ip6q_nxt = ip6f->ip6f_nxt;
586 /* XXX ECN? */
587 }
588
589 /*
590 * Check that the reassembled packet would not exceed 65535 bytes
591 * in size.
592 * If it would exceed, discard the fragment and return an ICMP error.
593 */
594 if (q6->ip6q_unfrglen >= 0) {
595 /* The 1st fragment has already arrived. */
596 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
597 if (only_frag) {
598 TAILQ_REMOVE(head, q6, ip6q_tq);
599 V_ip6qb[bucket].count--;
600 atomic_subtract_int(&V_frag6_nfragpackets, 1);
601 #ifdef MAC
602 mac_ip6q_destroy(q6);
603 #endif
604 free(q6, M_FRAG6);
605 }
606 IP6QB_UNLOCK(bucket);
607 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
608 offset - sizeof(struct ip6_frag) +
609 offsetof(struct ip6_frag, ip6f_offlg));
610 *mp = NULL;
611 return (IPPROTO_DONE);
612 }
613 } else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
614 if (only_frag) {
615 TAILQ_REMOVE(head, q6, ip6q_tq);
616 V_ip6qb[bucket].count--;
617 atomic_subtract_int(&V_frag6_nfragpackets, 1);
618 #ifdef MAC
619 mac_ip6q_destroy(q6);
620 #endif
621 free(q6, M_FRAG6);
622 }
623 IP6QB_UNLOCK(bucket);
624 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
625 offset - sizeof(struct ip6_frag) +
626 offsetof(struct ip6_frag, ip6f_offlg));
627 *mp = NULL;
628 return (IPPROTO_DONE);
629 }
630
631 /*
632 * If it is the first fragment, do the above check for each
633 * fragment already stored in the reassembly queue.
634 */
635 if (fragoff == 0 && !only_frag) {
636 TAILQ_FOREACH_SAFE(af6, &q6->ip6q_frags, ip6af_tq, af6tmp) {
637
638 if (q6->ip6q_unfrglen + af6->ip6af_off +
639 af6->ip6af_frglen > IPV6_MAXPACKET) {
640 struct ip6_hdr *ip6err;
641 struct mbuf *merr;
642 int erroff;
643
644 merr = af6->ip6af_m;
645 erroff = af6->ip6af_offset;
646
647 /* Dequeue the fragment. */
648 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq);
649 q6->ip6q_nfrag--;
650 atomic_subtract_int(&frag6_nfrags, 1);
651 free(af6, M_FRAG6);
652
653 /* Set a valid receive interface pointer. */
654 merr->m_pkthdr.rcvif = srcifp;
655
656 /* Adjust pointer. */
657 ip6err = mtod(merr, struct ip6_hdr *);
658
659 /*
660 * Restore source and destination addresses
661 * in the erroneous IPv6 header.
662 */
663 ip6err->ip6_src = q6->ip6q_src;
664 ip6err->ip6_dst = q6->ip6q_dst;
665
666 icmp6_error(merr, ICMP6_PARAM_PROB,
667 ICMP6_PARAMPROB_HEADER,
668 erroff - sizeof(struct ip6_frag) +
669 offsetof(struct ip6_frag, ip6f_offlg));
670 }
671 }
672 }
673
674 /* Allocate an IPv6 fragement queue entry for this fragmented part. */
675 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FRAG6,
676 M_NOWAIT | M_ZERO);
677 if (ip6af == NULL)
678 goto dropfrag;
679 ip6af->ip6af_mff = (ip6f->ip6f_offlg & IP6F_MORE_FRAG) ? true : false;
680 ip6af->ip6af_off = fragoff;
681 ip6af->ip6af_frglen = frgpartlen;
682 ip6af->ip6af_offset = offset;
683 ip6af->ip6af_m = m;
684
685 if (only_frag) {
686 /*
687 * Do a manual insert rather than a hard-to-understand cast
688 * to a different type relying on data structure order to work.
689 */
690 TAILQ_INSERT_HEAD(&q6->ip6q_frags, ip6af, ip6af_tq);
691 goto postinsert;
692 }
693
694 /* Do duplicate, condition, and boundry checks. */
695 /*
696 * Handle ECN by comparing this segment with the first one;
697 * if CE is set, do not lose CE.
698 * Drop if CE and not-ECT are mixed for the same packet.
699 */
700 ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK;
701 ecn0 = q6->ip6q_ecn;
702 if (ecn == IPTOS_ECN_CE) {
703 if (ecn0 == IPTOS_ECN_NOTECT) {
704 free(ip6af, M_FRAG6);
705 goto dropfrag;
706 }
707 if (ecn0 != IPTOS_ECN_CE)
708 q6->ip6q_ecn = IPTOS_ECN_CE;
709 }
710 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) {
711 free(ip6af, M_FRAG6);
712 goto dropfrag;
713 }
714
715 /* Find a fragmented part which begins after this one does. */
716 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq)
717 if (af6->ip6af_off > ip6af->ip6af_off)
718 break;
719
720 /*
721 * If the incoming framgent overlaps some existing fragments in
722 * the reassembly queue, drop both the new fragment and the
723 * entire reassembly queue. However, if the new fragment
724 * is an exact duplicate of an existing fragment, only silently
725 * drop the existing fragment and leave the fragmentation queue
726 * unchanged, as allowed by the RFC. (RFC 8200, 4.5)
727 */
728 if (af6 != NULL)
729 af6tmp = TAILQ_PREV(af6, ip6fraghead, ip6af_tq);
730 else
731 af6tmp = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead);
732 if (af6tmp != NULL) {
733 if (af6tmp->ip6af_off + af6tmp->ip6af_frglen -
734 ip6af->ip6af_off > 0) {
735 if (af6tmp->ip6af_off != ip6af->ip6af_off ||
736 af6tmp->ip6af_frglen != ip6af->ip6af_frglen)
737 frag6_freef(q6, bucket);
738 free(ip6af, M_FRAG6);
739 goto dropfrag;
740 }
741 }
742 if (af6 != NULL) {
743 if (ip6af->ip6af_off + ip6af->ip6af_frglen -
744 af6->ip6af_off > 0) {
745 if (af6->ip6af_off != ip6af->ip6af_off ||
746 af6->ip6af_frglen != ip6af->ip6af_frglen)
747 frag6_freef(q6, bucket);
748 free(ip6af, M_FRAG6);
749 goto dropfrag;
750 }
751 }
752
753 #ifdef MAC
754 mac_ip6q_update(m, q6);
755 #endif
756
757 /*
758 * Stick new segment in its place; check for complete reassembly.
759 * If not complete, check fragment limit. Move to front of packet
760 * queue, as we are the most recently active fragmented packet.
761 */
762 if (af6 != NULL)
763 TAILQ_INSERT_BEFORE(af6, ip6af, ip6af_tq);
764 else
765 TAILQ_INSERT_TAIL(&q6->ip6q_frags, ip6af, ip6af_tq);
766 postinsert:
767 atomic_add_int(&frag6_nfrags, 1);
768 q6->ip6q_nfrag++;
769
770 plen = 0;
771 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) {
772 if (af6->ip6af_off != plen) {
773 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) {
774 IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag);
775 frag6_freef(q6, bucket);
776 }
777 IP6QB_UNLOCK(bucket);
778 *mp = NULL;
779 return (IPPROTO_DONE);
780 }
781 plen += af6->ip6af_frglen;
782 }
783 af6 = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead);
784 if (af6->ip6af_mff) {
785 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) {
786 IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag);
787 frag6_freef(q6, bucket);
788 }
789 IP6QB_UNLOCK(bucket);
790 *mp = NULL;
791 return (IPPROTO_DONE);
792 }
793
794 /* Reassembly is complete; concatenate fragments. */
795 ip6af = TAILQ_FIRST(&q6->ip6q_frags);
796 t = m = ip6af->ip6af_m;
797 TAILQ_REMOVE(&q6->ip6q_frags, ip6af, ip6af_tq);
798 while ((af6 = TAILQ_FIRST(&q6->ip6q_frags)) != NULL) {
799 m->m_pkthdr.csum_flags &=
800 af6->ip6af_m->m_pkthdr.csum_flags;
801 m->m_pkthdr.csum_data +=
802 af6->ip6af_m->m_pkthdr.csum_data;
803
804 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq);
805 t = m_last(t);
806 m_adj(af6->ip6af_m, af6->ip6af_offset);
807 m_demote_pkthdr(af6->ip6af_m);
808 m_cat(t, af6->ip6af_m);
809 free(af6, M_FRAG6);
810 }
811
812 while (m->m_pkthdr.csum_data & 0xffff0000)
813 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) +
814 (m->m_pkthdr.csum_data >> 16);
815
816 /* Adjust offset to point where the original next header starts. */
817 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
818 free(ip6af, M_FRAG6);
819 ip6 = mtod(m, struct ip6_hdr *);
820 ip6->ip6_plen = htons((u_short)plen + offset - sizeof(struct ip6_hdr));
821 if (q6->ip6q_ecn == IPTOS_ECN_CE)
822 ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20);
823 nxt = q6->ip6q_nxt;
824
825 TAILQ_REMOVE(head, q6, ip6q_tq);
826 V_ip6qb[bucket].count--;
827 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag);
828
829 ip6_deletefraghdr(m, offset, M_NOWAIT);
830
831 /* Set nxt(-hdr field value) to the original value. */
832 m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t),
833 (caddr_t)&nxt);
834
835 #ifdef MAC
836 mac_ip6q_reassemble(q6, m);
837 mac_ip6q_destroy(q6);
838 #endif
839 free(q6, M_FRAG6);
840 atomic_subtract_int(&V_frag6_nfragpackets, 1);
841
842 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
843
844 plen = 0;
845 for (t = m; t; t = t->m_next)
846 plen += t->m_len;
847 m->m_pkthdr.len = plen;
848 /* Set a valid receive interface pointer. */
849 m->m_pkthdr.rcvif = srcifp;
850 }
851
852 #ifdef RSS
853 mtag = m_tag_alloc(MTAG_ABI_IPV6, IPV6_TAG_DIRECT, sizeof(*ip6dc),
854 M_NOWAIT);
855 if (mtag == NULL)
856 goto dropfrag;
857
858 ip6dc = (struct ip6_direct_ctx *)(mtag + 1);
859 ip6dc->ip6dc_nxt = nxt;
860 ip6dc->ip6dc_off = offset;
861
862 m_tag_prepend(m, mtag);
863 #endif
864
865 IP6QB_UNLOCK(bucket);
866 IP6STAT_INC(ip6s_reassembled);
867 in6_ifstat_inc(dstifp, ifs6_reass_ok);
868
869 #ifdef RSS
870 /* Queue/dispatch for reprocessing. */
871 netisr_dispatch(NETISR_IPV6_DIRECT, m);
872 *mp = NULL;
873 return (IPPROTO_DONE);
874 #endif
875
876 /* Tell launch routine the next header. */
877 *mp = m;
878 *offp = offset;
879
880 return (nxt);
881
882 dropfrag:
883 IP6QB_UNLOCK(bucket);
884 dropfrag2:
885 in6_ifstat_inc(dstifp, ifs6_reass_fail);
886 IP6STAT_INC(ip6s_fragdropped);
887 m_freem(m);
888 *mp = NULL;
889 return (IPPROTO_DONE);
890 }
891
892 /*
893 * IPv6 reassembling timer processing;
894 * if a timer expires on a reassembly queue, discard it.
895 */
896 void
897 frag6_slowtimo(void)
898 {
899 VNET_ITERATOR_DECL(vnet_iter);
900 struct ip6qhead *head;
901 struct ip6q *q6, *q6tmp;
902 uint32_t bucket;
903
904 if (atomic_load_int(&frag6_nfrags) == 0)
905 return;
906
907 VNET_LIST_RLOCK_NOSLEEP();
908 VNET_FOREACH(vnet_iter) {
909 CURVNET_SET(vnet_iter);
910 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
911 if (V_ip6qb[bucket].count == 0)
912 continue;
913 IP6QB_LOCK(bucket);
914 head = IP6QB_HEAD(bucket);
915 TAILQ_FOREACH_SAFE(q6, head, ip6q_tq, q6tmp)
916 if (--q6->ip6q_ttl == 0) {
917 IP6STAT_ADD(ip6s_fragtimeout,
918 q6->ip6q_nfrag);
919 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
920 frag6_freef(q6, bucket);
921 }
922 /*
923 * If we are over the maximum number of fragments
924 * (due to the limit being lowered), drain off
925 * enough to get down to the new limit.
926 * Note that we drain all reassembly queues if
927 * maxfragpackets is 0 (fragmentation is disabled),
928 * and do not enforce a limit when maxfragpackets
929 * is negative.
930 */
931 while ((V_ip6_maxfragpackets == 0 ||
932 (V_ip6_maxfragpackets > 0 &&
933 V_ip6qb[bucket].count > V_ip6_maxfragbucketsize)) &&
934 (q6 = TAILQ_LAST(head, ip6qhead)) != NULL) {
935 IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag);
936 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
937 frag6_freef(q6, bucket);
938 }
939 IP6QB_UNLOCK(bucket);
940 }
941 /*
942 * If we are still over the maximum number of fragmented
943 * packets, drain off enough to get down to the new limit.
944 */
945 bucket = 0;
946 while (V_ip6_maxfragpackets >= 0 &&
947 atomic_load_int(&V_frag6_nfragpackets) >
948 (u_int)V_ip6_maxfragpackets) {
949 IP6QB_LOCK(bucket);
950 q6 = TAILQ_LAST(IP6QB_HEAD(bucket), ip6qhead);
951 if (q6 != NULL) {
952 IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag);
953 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
954 frag6_freef(q6, bucket);
955 }
956 IP6QB_UNLOCK(bucket);
957 bucket = (bucket + 1) % IP6REASS_NHASH;
958 }
959 CURVNET_RESTORE();
960 }
961 VNET_LIST_RUNLOCK_NOSLEEP();
962 }
963
964 /*
965 * Eventhandler to adjust limits in case nmbclusters change.
966 */
967 static void
968 frag6_change(void *tag)
969 {
970 VNET_ITERATOR_DECL(vnet_iter);
971
972 ip6_maxfrags = IP6_MAXFRAGS;
973 VNET_LIST_RLOCK_NOSLEEP();
974 VNET_FOREACH(vnet_iter) {
975 CURVNET_SET(vnet_iter);
976 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS;
977 frag6_set_bucketsize();
978 CURVNET_RESTORE();
979 }
980 VNET_LIST_RUNLOCK_NOSLEEP();
981 }
982
983 /*
984 * Initialise reassembly queue and fragment identifier.
985 */
986 void
987 frag6_init(void)
988 {
989 uint32_t bucket;
990
991 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS;
992 frag6_set_bucketsize();
993 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
994 TAILQ_INIT(IP6QB_HEAD(bucket));
995 mtx_init(&V_ip6qb[bucket].lock, "ip6qb", NULL, MTX_DEF);
996 V_ip6qb[bucket].count = 0;
997 }
998 V_ip6qb_hashseed = arc4random();
999 V_ip6_maxfragsperpacket = 64;
1000 #ifdef VIMAGE
1001 V_frag6_on = true;
1002 #endif
1003 if (!IS_DEFAULT_VNET(curvnet))
1004 return;
1005
1006 ip6_maxfrags = IP6_MAXFRAGS;
1007 EVENTHANDLER_REGISTER(nmbclusters_change,
1008 frag6_change, NULL, EVENTHANDLER_PRI_ANY);
1009 }
1010
1011 /*
1012 * Drain off all datagram fragments.
1013 */
1014 static void
1015 frag6_drain_one(void)
1016 {
1017 struct ip6q *q6;
1018 uint32_t bucket;
1019
1020 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
1021 IP6QB_LOCK(bucket);
1022 while ((q6 = TAILQ_FIRST(IP6QB_HEAD(bucket))) != NULL) {
1023 IP6STAT_INC(ip6s_fragdropped);
1024 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
1025 frag6_freef(q6, bucket);
1026 }
1027 IP6QB_UNLOCK(bucket);
1028 }
1029 }
1030
1031 void
1032 frag6_drain(void)
1033 {
1034 VNET_ITERATOR_DECL(vnet_iter);
1035
1036 VNET_LIST_RLOCK_NOSLEEP();
1037 VNET_FOREACH(vnet_iter) {
1038 CURVNET_SET(vnet_iter);
1039 frag6_drain_one();
1040 CURVNET_RESTORE();
1041 }
1042 VNET_LIST_RUNLOCK_NOSLEEP();
1043 }
1044
1045 #ifdef VIMAGE
1046 /*
1047 * Clear up IPv6 reassembly structures.
1048 */
1049 void
1050 frag6_destroy(void)
1051 {
1052 uint32_t bucket;
1053
1054 frag6_drain_one();
1055 V_frag6_on = false;
1056 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
1057 KASSERT(V_ip6qb[bucket].count == 0,
1058 ("%s: V_ip6qb[%d] (%p) count not 0 (%d)", __func__,
1059 bucket, &V_ip6qb[bucket], V_ip6qb[bucket].count));
1060 mtx_destroy(&V_ip6qb[bucket].lock);
1061 }
1062 }
1063 #endif
Cache object: 018f050a140e5678ee6033585d25ef67
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