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 * Sysctls and helper function.
163 */
164 SYSCTL_DECL(_net_inet6_ip6);
165
166 SYSCTL_UINT(_net_inet6_ip6, OID_AUTO, frag6_nfrags,
167 CTLFLAG_RD, &frag6_nfrags, 0,
168 "Global number of IPv6 fragments across all reassembly queues.");
169
170 static void
171 frag6_set_bucketsize(void)
172 {
173 int i;
174
175 if ((i = V_ip6_maxfragpackets) > 0)
176 V_ip6_maxfragbucketsize = imax(i / (IP6REASS_NHASH / 2), 1);
177 }
178
179 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGS, maxfrags,
180 CTLFLAG_RW, &ip6_maxfrags, 0,
181 "Maximum allowed number of outstanding IPv6 packet fragments. "
182 "A value of 0 means no fragmented packets will be accepted, while "
183 "a value of -1 means no limit");
184
185 static int
186 sysctl_ip6_maxfragpackets(SYSCTL_HANDLER_ARGS)
187 {
188 int error, val;
189
190 val = V_ip6_maxfragpackets;
191 error = sysctl_handle_int(oidp, &val, 0, req);
192 if (error != 0 || !req->newptr)
193 return (error);
194 V_ip6_maxfragpackets = val;
195 frag6_set_bucketsize();
196 return (0);
197 }
198 SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_MAXFRAGPACKETS, maxfragpackets,
199 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
200 NULL, 0, sysctl_ip6_maxfragpackets, "I",
201 "Default maximum number of outstanding fragmented IPv6 packets. "
202 "A value of 0 means no fragmented packets will be accepted, while a "
203 "a value of -1 means no limit");
204 SYSCTL_UINT(_net_inet6_ip6, OID_AUTO, frag6_nfragpackets,
205 CTLFLAG_VNET | CTLFLAG_RD,
206 __DEVOLATILE(u_int *, &VNET_NAME(frag6_nfragpackets)), 0,
207 "Per-VNET number of IPv6 fragments across all reassembly queues.");
208 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGSPERPACKET, maxfragsperpacket,
209 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_maxfragsperpacket), 0,
210 "Maximum allowed number of fragments per packet");
211 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_MAXFRAGBUCKETSIZE, maxfragbucketsize,
212 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_maxfragbucketsize), 0,
213 "Maximum number of reassembly queues per hash bucket");
214
215 /*
216 * Remove the IPv6 fragmentation header from the mbuf.
217 */
218 int
219 ip6_deletefraghdr(struct mbuf *m, int offset, int wait __unused)
220 {
221 struct ip6_hdr *ip6;
222
223 KASSERT(m->m_len >= offset + sizeof(struct ip6_frag),
224 ("%s: ext headers not contigous in mbuf %p m_len %d >= "
225 "offset %d + %zu\n", __func__, m, m->m_len, offset,
226 sizeof(struct ip6_frag)));
227
228 /* Delete frag6 header. */
229 ip6 = mtod(m, struct ip6_hdr *);
230 bcopy(ip6, (char *)ip6 + sizeof(struct ip6_frag), offset);
231 m->m_data += sizeof(struct ip6_frag);
232 m->m_len -= sizeof(struct ip6_frag);
233 m->m_flags |= M_FRAGMENTED;
234
235 return (0);
236 }
237
238 /*
239 * Free a fragment reassembly header and all associated datagrams.
240 */
241 static void
242 frag6_freef(struct ip6q *q6, uint32_t bucket)
243 {
244 struct ip6_hdr *ip6;
245 struct ip6asfrag *af6;
246 struct mbuf *m;
247
248 IP6QB_LOCK_ASSERT(bucket);
249
250 while ((af6 = TAILQ_FIRST(&q6->ip6q_frags)) != NULL) {
251 m = af6->ip6af_m;
252 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq);
253
254 /*
255 * Return ICMP time exceeded error for the 1st fragment.
256 * Just free other fragments.
257 */
258 if (af6->ip6af_off == 0 && m->m_pkthdr.rcvif != NULL) {
259 /* Adjust pointer. */
260 ip6 = mtod(m, struct ip6_hdr *);
261
262 /* Restore source and destination addresses. */
263 ip6->ip6_src = q6->ip6q_src;
264 ip6->ip6_dst = q6->ip6q_dst;
265
266 icmp6_error(m, ICMP6_TIME_EXCEEDED,
267 ICMP6_TIME_EXCEED_REASSEMBLY, 0);
268 } else
269 m_freem(m);
270
271 free(af6, M_FRAG6);
272 }
273
274 TAILQ_REMOVE(IP6QB_HEAD(bucket), q6, ip6q_tq);
275 V_ip6qb[bucket].count--;
276 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag);
277 #ifdef MAC
278 mac_ip6q_destroy(q6);
279 #endif
280 free(q6, M_FRAG6);
281 atomic_subtract_int(&V_frag6_nfragpackets, 1);
282 }
283
284 /*
285 * Drain off all datagram fragments belonging to
286 * the given network interface.
287 */
288 static void
289 frag6_cleanup(void *arg __unused, struct ifnet *ifp)
290 {
291 struct ip6qhead *head;
292 struct ip6q *q6;
293 struct ip6asfrag *af6;
294 uint32_t bucket;
295
296 KASSERT(ifp != NULL, ("%s: ifp is NULL", __func__));
297
298 CURVNET_SET_QUIET(ifp->if_vnet);
299 #ifdef VIMAGE
300 /*
301 * Skip processing if IPv6 reassembly is not initialised or
302 * torn down by frag6_destroy().
303 */
304 if (!V_frag6_on) {
305 CURVNET_RESTORE();
306 return;
307 }
308 #endif
309
310 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
311 IP6QB_LOCK(bucket);
312 head = IP6QB_HEAD(bucket);
313 /* Scan fragment list. */
314 TAILQ_FOREACH(q6, head, ip6q_tq) {
315 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) {
316 /* Clear no longer valid rcvif pointer. */
317 if (af6->ip6af_m->m_pkthdr.rcvif == ifp)
318 af6->ip6af_m->m_pkthdr.rcvif = NULL;
319 }
320 }
321 IP6QB_UNLOCK(bucket);
322 }
323 CURVNET_RESTORE();
324 }
325 EVENTHANDLER_DEFINE(ifnet_departure_event, frag6_cleanup, NULL, 0);
326
327 /*
328 * Like in RFC2460, in RFC8200, fragment and reassembly rules do not agree with
329 * each other, in terms of next header field handling in fragment header.
330 * While the sender will use the same value for all of the fragmented packets,
331 * receiver is suggested not to check for consistency.
332 *
333 * Fragment rules (p18,p19):
334 * (2) A Fragment header containing:
335 * The Next Header value that identifies the first header
336 * after the Per-Fragment headers of the original packet.
337 * -> next header field is same for all fragments
338 *
339 * Reassembly rule (p20):
340 * The Next Header field of the last header of the Per-Fragment
341 * headers is obtained from the Next Header field of the first
342 * fragment's Fragment header.
343 * -> should grab it from the first fragment only
344 *
345 * The following note also contradicts with fragment rule - no one is going to
346 * send different fragment with different next header field.
347 *
348 * Additional note (p22) [not an error]:
349 * The Next Header values in the Fragment headers of different
350 * fragments of the same original packet may differ. Only the value
351 * from the Offset zero fragment packet is used for reassembly.
352 * -> should grab it from the first fragment only
353 *
354 * There is no explicit reason given in the RFC. Historical reason maybe?
355 */
356 /*
357 * Fragment input.
358 */
359 int
360 frag6_input(struct mbuf **mp, int *offp, int proto)
361 {
362 struct mbuf *m, *t;
363 struct ip6_hdr *ip6;
364 struct ip6_frag *ip6f;
365 struct ip6qhead *head;
366 struct ip6q *q6;
367 struct ip6asfrag *af6, *ip6af, *af6tmp;
368 struct in6_ifaddr *ia6;
369 struct ifnet *dstifp, *srcifp;
370 uint32_t hashkey[(sizeof(struct in6_addr) * 2 +
371 sizeof(ip6f->ip6f_ident)) / sizeof(uint32_t)];
372 uint32_t bucket, *hashkeyp;
373 int fragoff, frgpartlen; /* Must be larger than uint16_t. */
374 int nxt, offset, plen;
375 uint8_t ecn, ecn0;
376 bool only_frag;
377 #ifdef RSS
378 struct ip6_direct_ctx *ip6dc;
379 struct m_tag *mtag;
380 #endif
381
382 m = *mp;
383 offset = *offp;
384
385 M_ASSERTPKTHDR(m);
386
387 if (m->m_len < offset + sizeof(struct ip6_frag)) {
388 m = m_pullup(m, offset + sizeof(struct ip6_frag));
389 if (m == NULL) {
390 IP6STAT_INC(ip6s_exthdrtoolong);
391 *mp = NULL;
392 return (IPPROTO_DONE);
393 }
394 }
395 ip6 = mtod(m, struct ip6_hdr *);
396
397 dstifp = NULL;
398 /* Find the destination interface of the packet. */
399 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false);
400 if (ia6 != NULL)
401 dstifp = ia6->ia_ifp;
402
403 /* Jumbo payload cannot contain a fragment header. */
404 if (ip6->ip6_plen == 0) {
405 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
406 in6_ifstat_inc(dstifp, ifs6_reass_fail);
407 *mp = NULL;
408 return (IPPROTO_DONE);
409 }
410
411 /*
412 * Check whether fragment packet's fragment length is a
413 * multiple of 8 octets (unless it is the last one).
414 * sizeof(struct ip6_frag) == 8
415 * sizeof(struct ip6_hdr) = 40
416 */
417 ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset);
418 if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
419 (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
420 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
421 offsetof(struct ip6_hdr, ip6_plen));
422 in6_ifstat_inc(dstifp, ifs6_reass_fail);
423 *mp = NULL;
424 return (IPPROTO_DONE);
425 }
426
427 IP6STAT_INC(ip6s_fragments);
428 in6_ifstat_inc(dstifp, ifs6_reass_reqd);
429
430 /*
431 * Handle "atomic" fragments (offset and m bit set to 0) upfront,
432 * unrelated to any reassembly. We need to remove the frag hdr
433 * which is ugly.
434 * See RFC 6946 and section 4.5 of RFC 8200.
435 */
436 if ((ip6f->ip6f_offlg & ~IP6F_RESERVED_MASK) == 0) {
437 IP6STAT_INC(ip6s_atomicfrags);
438 nxt = ip6f->ip6f_nxt;
439 /*
440 * Set nxt(-hdr field value) to the original value.
441 * We cannot just set ip6->ip6_nxt as there might be
442 * an unfragmentable part with extension headers and
443 * we must update the last one.
444 */
445 m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t),
446 (caddr_t)&nxt);
447 ip6->ip6_plen = htons(ntohs(ip6->ip6_plen) -
448 sizeof(struct ip6_frag));
449 if (ip6_deletefraghdr(m, offset, M_NOWAIT) != 0)
450 goto dropfrag2;
451 m->m_pkthdr.len -= sizeof(struct ip6_frag);
452 in6_ifstat_inc(dstifp, ifs6_reass_ok);
453 *mp = m;
454 return (nxt);
455 }
456
457 /* Offset now points to data portion. */
458 offset += sizeof(struct ip6_frag);
459
460 /* Get fragment length and discard 0-byte fragments. */
461 frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
462 if (frgpartlen == 0) {
463 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
464 offsetof(struct ip6_hdr, ip6_plen));
465 in6_ifstat_inc(dstifp, ifs6_reass_fail);
466 IP6STAT_INC(ip6s_fragdropped);
467 *mp = NULL;
468 return (IPPROTO_DONE);
469 }
470
471 /*
472 * Enforce upper bound on number of fragments for the entire system.
473 * If maxfrag is 0, never accept fragments.
474 * If maxfrag is -1, accept all fragments without limitation.
475 */
476 if (ip6_maxfrags < 0)
477 ;
478 else if (atomic_load_int(&frag6_nfrags) >= (u_int)ip6_maxfrags)
479 goto dropfrag2;
480
481 /*
482 * Validate that a full header chain to the ULP is present in the
483 * packet containing the first fragment as per RFC RFC7112 and
484 * RFC 8200 pages 18,19:
485 * The first fragment packet is composed of:
486 * (3) Extension headers, if any, and the Upper-Layer header. These
487 * headers must be in the first fragment. ...
488 */
489 fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
490 /* XXX TODO. thj has D16851 open for this. */
491 /* Send ICMPv6 4,3 in case of violation. */
492
493 /* Store receive network interface pointer for later. */
494 srcifp = m->m_pkthdr.rcvif;
495
496 /* Generate a hash value for fragment bucket selection. */
497 hashkeyp = hashkey;
498 memcpy(hashkeyp, &ip6->ip6_src, sizeof(struct in6_addr));
499 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp);
500 memcpy(hashkeyp, &ip6->ip6_dst, sizeof(struct in6_addr));
501 hashkeyp += sizeof(struct in6_addr) / sizeof(*hashkeyp);
502 *hashkeyp = ip6f->ip6f_ident;
503 bucket = jenkins_hash32(hashkey, nitems(hashkey), V_ip6qb_hashseed);
504 bucket &= IP6REASS_HMASK;
505 IP6QB_LOCK(bucket);
506 head = IP6QB_HEAD(bucket);
507
508 TAILQ_FOREACH(q6, head, ip6q_tq)
509 if (ip6f->ip6f_ident == q6->ip6q_ident &&
510 IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
511 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst)
512 #ifdef MAC
513 && mac_ip6q_match(m, q6)
514 #endif
515 )
516 break;
517
518 only_frag = false;
519 if (q6 == NULL) {
520 /* A first fragment to arrive creates a reassembly queue. */
521 only_frag = true;
522
523 /*
524 * Enforce upper bound on number of fragmented packets
525 * for which we attempt reassembly;
526 * If maxfragpackets is 0, never accept fragments.
527 * If maxfragpackets is -1, accept all fragments without
528 * limitation.
529 */
530 if (V_ip6_maxfragpackets < 0)
531 ;
532 else if (V_ip6qb[bucket].count >= V_ip6_maxfragbucketsize ||
533 atomic_load_int(&V_frag6_nfragpackets) >=
534 (u_int)V_ip6_maxfragpackets)
535 goto dropfrag;
536
537 /* Allocate IPv6 fragement packet queue entry. */
538 q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FRAG6,
539 M_NOWAIT | M_ZERO);
540 if (q6 == NULL)
541 goto dropfrag;
542 #ifdef MAC
543 if (mac_ip6q_init(q6, M_NOWAIT) != 0) {
544 free(q6, M_FRAG6);
545 goto dropfrag;
546 }
547 mac_ip6q_create(m, q6);
548 #endif
549 atomic_add_int(&V_frag6_nfragpackets, 1);
550
551 /* ip6q_nxt will be filled afterwards, from 1st fragment. */
552 TAILQ_INIT(&q6->ip6q_frags);
553 q6->ip6q_ident = ip6f->ip6f_ident;
554 q6->ip6q_ttl = IPV6_FRAGTTL;
555 q6->ip6q_src = ip6->ip6_src;
556 q6->ip6q_dst = ip6->ip6_dst;
557 q6->ip6q_ecn = IPV6_ECN(ip6);
558 q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
559
560 /* Add the fragemented packet to the bucket. */
561 TAILQ_INSERT_HEAD(head, q6, ip6q_tq);
562 V_ip6qb[bucket].count++;
563 }
564
565 /*
566 * If it is the 1st fragment, record the length of the
567 * unfragmentable part and the next header of the fragment header.
568 * Assume the first 1st fragement to arrive will be correct.
569 * We do not have any duplicate checks here yet so another packet
570 * with fragoff == 0 could come and overwrite the ip6q_unfrglen
571 * and worse, the next header, at any time.
572 */
573 if (fragoff == 0 && q6->ip6q_unfrglen == -1) {
574 q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr) -
575 sizeof(struct ip6_frag);
576 q6->ip6q_nxt = ip6f->ip6f_nxt;
577 /* XXX ECN? */
578 }
579
580 /*
581 * Check that the reassembled packet would not exceed 65535 bytes
582 * in size.
583 * If it would exceed, discard the fragment and return an ICMP error.
584 */
585 if (q6->ip6q_unfrglen >= 0) {
586 /* The 1st fragment has already arrived. */
587 if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
588 if (only_frag) {
589 TAILQ_REMOVE(head, q6, ip6q_tq);
590 V_ip6qb[bucket].count--;
591 atomic_subtract_int(&V_frag6_nfragpackets, 1);
592 #ifdef MAC
593 mac_ip6q_destroy(q6);
594 #endif
595 free(q6, M_FRAG6);
596 }
597 IP6QB_UNLOCK(bucket);
598 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
599 offset - sizeof(struct ip6_frag) +
600 offsetof(struct ip6_frag, ip6f_offlg));
601 *mp = NULL;
602 return (IPPROTO_DONE);
603 }
604 } else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
605 if (only_frag) {
606 TAILQ_REMOVE(head, q6, ip6q_tq);
607 V_ip6qb[bucket].count--;
608 atomic_subtract_int(&V_frag6_nfragpackets, 1);
609 #ifdef MAC
610 mac_ip6q_destroy(q6);
611 #endif
612 free(q6, M_FRAG6);
613 }
614 IP6QB_UNLOCK(bucket);
615 icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
616 offset - sizeof(struct ip6_frag) +
617 offsetof(struct ip6_frag, ip6f_offlg));
618 *mp = NULL;
619 return (IPPROTO_DONE);
620 }
621
622 /*
623 * If it is the first fragment, do the above check for each
624 * fragment already stored in the reassembly queue.
625 */
626 if (fragoff == 0 && !only_frag) {
627 TAILQ_FOREACH_SAFE(af6, &q6->ip6q_frags, ip6af_tq, af6tmp) {
628 if (q6->ip6q_unfrglen + af6->ip6af_off +
629 af6->ip6af_frglen > IPV6_MAXPACKET) {
630 struct ip6_hdr *ip6err;
631 struct mbuf *merr;
632 int erroff;
633
634 merr = af6->ip6af_m;
635 erroff = af6->ip6af_offset;
636
637 /* Dequeue the fragment. */
638 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq);
639 q6->ip6q_nfrag--;
640 atomic_subtract_int(&frag6_nfrags, 1);
641 free(af6, M_FRAG6);
642
643 /* Set a valid receive interface pointer. */
644 merr->m_pkthdr.rcvif = srcifp;
645
646 /* Adjust pointer. */
647 ip6err = mtod(merr, struct ip6_hdr *);
648
649 /*
650 * Restore source and destination addresses
651 * in the erroneous IPv6 header.
652 */
653 ip6err->ip6_src = q6->ip6q_src;
654 ip6err->ip6_dst = q6->ip6q_dst;
655
656 icmp6_error(merr, ICMP6_PARAM_PROB,
657 ICMP6_PARAMPROB_HEADER,
658 erroff - sizeof(struct ip6_frag) +
659 offsetof(struct ip6_frag, ip6f_offlg));
660 }
661 }
662 }
663
664 /* Allocate an IPv6 fragement queue entry for this fragmented part. */
665 ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FRAG6,
666 M_NOWAIT | M_ZERO);
667 if (ip6af == NULL)
668 goto dropfrag;
669 ip6af->ip6af_mff = (ip6f->ip6f_offlg & IP6F_MORE_FRAG) ? true : false;
670 ip6af->ip6af_off = fragoff;
671 ip6af->ip6af_frglen = frgpartlen;
672 ip6af->ip6af_offset = offset;
673 ip6af->ip6af_m = m;
674
675 if (only_frag) {
676 /*
677 * Do a manual insert rather than a hard-to-understand cast
678 * to a different type relying on data structure order to work.
679 */
680 TAILQ_INSERT_HEAD(&q6->ip6q_frags, ip6af, ip6af_tq);
681 goto postinsert;
682 }
683
684 /* Do duplicate, condition, and boundry checks. */
685 /*
686 * Handle ECN by comparing this segment with the first one;
687 * if CE is set, do not lose CE.
688 * Drop if CE and not-ECT are mixed for the same packet.
689 */
690 ecn = IPV6_ECN(ip6);
691 ecn0 = q6->ip6q_ecn;
692 if (ecn == IPTOS_ECN_CE) {
693 if (ecn0 == IPTOS_ECN_NOTECT) {
694 free(ip6af, M_FRAG6);
695 goto dropfrag;
696 }
697 if (ecn0 != IPTOS_ECN_CE)
698 q6->ip6q_ecn = IPTOS_ECN_CE;
699 }
700 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) {
701 free(ip6af, M_FRAG6);
702 goto dropfrag;
703 }
704
705 /* Find a fragmented part which begins after this one does. */
706 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq)
707 if (af6->ip6af_off > ip6af->ip6af_off)
708 break;
709
710 /*
711 * If the incoming framgent overlaps some existing fragments in
712 * the reassembly queue, drop both the new fragment and the
713 * entire reassembly queue. However, if the new fragment
714 * is an exact duplicate of an existing fragment, only silently
715 * drop the existing fragment and leave the fragmentation queue
716 * unchanged, as allowed by the RFC. (RFC 8200, 4.5)
717 */
718 if (af6 != NULL)
719 af6tmp = TAILQ_PREV(af6, ip6fraghead, ip6af_tq);
720 else
721 af6tmp = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead);
722 if (af6tmp != NULL) {
723 if (af6tmp->ip6af_off + af6tmp->ip6af_frglen -
724 ip6af->ip6af_off > 0) {
725 if (af6tmp->ip6af_off != ip6af->ip6af_off ||
726 af6tmp->ip6af_frglen != ip6af->ip6af_frglen)
727 frag6_freef(q6, bucket);
728 free(ip6af, M_FRAG6);
729 goto dropfrag;
730 }
731 }
732 if (af6 != NULL) {
733 if (ip6af->ip6af_off + ip6af->ip6af_frglen -
734 af6->ip6af_off > 0) {
735 if (af6->ip6af_off != ip6af->ip6af_off ||
736 af6->ip6af_frglen != ip6af->ip6af_frglen)
737 frag6_freef(q6, bucket);
738 free(ip6af, M_FRAG6);
739 goto dropfrag;
740 }
741 }
742
743 #ifdef MAC
744 mac_ip6q_update(m, q6);
745 #endif
746
747 /*
748 * Stick new segment in its place; check for complete reassembly.
749 * If not complete, check fragment limit. Move to front of packet
750 * queue, as we are the most recently active fragmented packet.
751 */
752 if (af6 != NULL)
753 TAILQ_INSERT_BEFORE(af6, ip6af, ip6af_tq);
754 else
755 TAILQ_INSERT_TAIL(&q6->ip6q_frags, ip6af, ip6af_tq);
756 postinsert:
757 atomic_add_int(&frag6_nfrags, 1);
758 q6->ip6q_nfrag++;
759
760 plen = 0;
761 TAILQ_FOREACH(af6, &q6->ip6q_frags, ip6af_tq) {
762 if (af6->ip6af_off != plen) {
763 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) {
764 IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag);
765 frag6_freef(q6, bucket);
766 }
767 IP6QB_UNLOCK(bucket);
768 *mp = NULL;
769 return (IPPROTO_DONE);
770 }
771 plen += af6->ip6af_frglen;
772 }
773 af6 = TAILQ_LAST(&q6->ip6q_frags, ip6fraghead);
774 if (af6->ip6af_mff) {
775 if (q6->ip6q_nfrag > V_ip6_maxfragsperpacket) {
776 IP6STAT_ADD(ip6s_fragdropped, q6->ip6q_nfrag);
777 frag6_freef(q6, bucket);
778 }
779 IP6QB_UNLOCK(bucket);
780 *mp = NULL;
781 return (IPPROTO_DONE);
782 }
783
784 /* Reassembly is complete; concatenate fragments. */
785 ip6af = TAILQ_FIRST(&q6->ip6q_frags);
786 t = m = ip6af->ip6af_m;
787 TAILQ_REMOVE(&q6->ip6q_frags, ip6af, ip6af_tq);
788 while ((af6 = TAILQ_FIRST(&q6->ip6q_frags)) != NULL) {
789 m->m_pkthdr.csum_flags &=
790 af6->ip6af_m->m_pkthdr.csum_flags;
791 m->m_pkthdr.csum_data +=
792 af6->ip6af_m->m_pkthdr.csum_data;
793
794 TAILQ_REMOVE(&q6->ip6q_frags, af6, ip6af_tq);
795 t = m_last(t);
796 m_adj(af6->ip6af_m, af6->ip6af_offset);
797 m_demote_pkthdr(af6->ip6af_m);
798 m_cat(t, af6->ip6af_m);
799 free(af6, M_FRAG6);
800 }
801
802 while (m->m_pkthdr.csum_data & 0xffff0000)
803 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) +
804 (m->m_pkthdr.csum_data >> 16);
805
806 /* Adjust offset to point where the original next header starts. */
807 offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
808 free(ip6af, M_FRAG6);
809 ip6 = mtod(m, struct ip6_hdr *);
810 ip6->ip6_plen = htons((u_short)plen + offset - sizeof(struct ip6_hdr));
811 if (q6->ip6q_ecn == IPTOS_ECN_CE)
812 ip6->ip6_flow |= htonl(IPTOS_ECN_CE << 20);
813 nxt = q6->ip6q_nxt;
814
815 TAILQ_REMOVE(head, q6, ip6q_tq);
816 V_ip6qb[bucket].count--;
817 atomic_subtract_int(&frag6_nfrags, q6->ip6q_nfrag);
818
819 ip6_deletefraghdr(m, offset, M_NOWAIT);
820
821 /* Set nxt(-hdr field value) to the original value. */
822 m_copyback(m, ip6_get_prevhdr(m, offset), sizeof(uint8_t),
823 (caddr_t)&nxt);
824
825 #ifdef MAC
826 mac_ip6q_reassemble(q6, m);
827 mac_ip6q_destroy(q6);
828 #endif
829 free(q6, M_FRAG6);
830 atomic_subtract_int(&V_frag6_nfragpackets, 1);
831
832 if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
833
834 plen = 0;
835 for (t = m; t; t = t->m_next)
836 plen += t->m_len;
837 m->m_pkthdr.len = plen;
838 /* Set a valid receive interface pointer. */
839 m->m_pkthdr.rcvif = srcifp;
840 }
841
842 #ifdef RSS
843 mtag = m_tag_alloc(MTAG_ABI_IPV6, IPV6_TAG_DIRECT, sizeof(*ip6dc),
844 M_NOWAIT);
845 if (mtag == NULL)
846 goto dropfrag;
847
848 ip6dc = (struct ip6_direct_ctx *)(mtag + 1);
849 ip6dc->ip6dc_nxt = nxt;
850 ip6dc->ip6dc_off = offset;
851
852 m_tag_prepend(m, mtag);
853 #endif
854
855 IP6QB_UNLOCK(bucket);
856 IP6STAT_INC(ip6s_reassembled);
857 in6_ifstat_inc(dstifp, ifs6_reass_ok);
858
859 #ifdef RSS
860 /* Queue/dispatch for reprocessing. */
861 netisr_dispatch(NETISR_IPV6_DIRECT, m);
862 *mp = NULL;
863 return (IPPROTO_DONE);
864 #endif
865
866 /* Tell launch routine the next header. */
867 *mp = m;
868 *offp = offset;
869
870 return (nxt);
871
872 dropfrag:
873 IP6QB_UNLOCK(bucket);
874 dropfrag2:
875 in6_ifstat_inc(dstifp, ifs6_reass_fail);
876 IP6STAT_INC(ip6s_fragdropped);
877 m_freem(m);
878 *mp = NULL;
879 return (IPPROTO_DONE);
880 }
881
882 /*
883 * IPv6 reassembling timer processing;
884 * if a timer expires on a reassembly queue, discard it.
885 */
886 static struct callout frag6_callout;
887 static void
888 frag6_slowtimo(void *arg __unused)
889 {
890 VNET_ITERATOR_DECL(vnet_iter);
891 struct ip6qhead *head;
892 struct ip6q *q6, *q6tmp;
893 uint32_t bucket;
894
895 if (atomic_load_int(&frag6_nfrags) == 0)
896 goto done;
897
898 VNET_LIST_RLOCK_NOSLEEP();
899 VNET_FOREACH(vnet_iter) {
900 CURVNET_SET(vnet_iter);
901 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
902 if (V_ip6qb[bucket].count == 0)
903 continue;
904 IP6QB_LOCK(bucket);
905 head = IP6QB_HEAD(bucket);
906 TAILQ_FOREACH_SAFE(q6, head, ip6q_tq, q6tmp)
907 if (--q6->ip6q_ttl == 0) {
908 IP6STAT_ADD(ip6s_fragtimeout,
909 q6->ip6q_nfrag);
910 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
911 frag6_freef(q6, bucket);
912 }
913 /*
914 * If we are over the maximum number of fragments
915 * (due to the limit being lowered), drain off
916 * enough to get down to the new limit.
917 * Note that we drain all reassembly queues if
918 * maxfragpackets is 0 (fragmentation is disabled),
919 * and do not enforce a limit when maxfragpackets
920 * is negative.
921 */
922 while ((V_ip6_maxfragpackets == 0 ||
923 (V_ip6_maxfragpackets > 0 &&
924 V_ip6qb[bucket].count > V_ip6_maxfragbucketsize)) &&
925 (q6 = TAILQ_LAST(head, ip6qhead)) != NULL) {
926 IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag);
927 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
928 frag6_freef(q6, bucket);
929 }
930 IP6QB_UNLOCK(bucket);
931 }
932 /*
933 * If we are still over the maximum number of fragmented
934 * packets, drain off enough to get down to the new limit.
935 */
936 bucket = 0;
937 while (V_ip6_maxfragpackets >= 0 &&
938 atomic_load_int(&V_frag6_nfragpackets) >
939 (u_int)V_ip6_maxfragpackets) {
940 IP6QB_LOCK(bucket);
941 q6 = TAILQ_LAST(IP6QB_HEAD(bucket), ip6qhead);
942 if (q6 != NULL) {
943 IP6STAT_ADD(ip6s_fragoverflow, q6->ip6q_nfrag);
944 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
945 frag6_freef(q6, bucket);
946 }
947 IP6QB_UNLOCK(bucket);
948 bucket = (bucket + 1) % IP6REASS_NHASH;
949 }
950 CURVNET_RESTORE();
951 }
952 VNET_LIST_RUNLOCK_NOSLEEP();
953 done:
954 callout_reset_sbt(&frag6_callout, SBT_1MS * 500, SBT_1MS * 10,
955 frag6_slowtimo, NULL, 0);
956 }
957
958 static void
959 frag6_slowtimo_init(void *arg __unused)
960 {
961
962 callout_init(&frag6_callout, 1);
963 callout_reset_sbt(&frag6_callout, SBT_1MS * 500, SBT_1MS * 10,
964 frag6_slowtimo, NULL, 0);
965 }
966 SYSINIT(frag6, SI_SUB_VNET_DONE, SI_ORDER_ANY, frag6_slowtimo_init, NULL);
967
968 /*
969 * Eventhandler to adjust limits in case nmbclusters change.
970 */
971 static void
972 frag6_change(void *tag)
973 {
974 VNET_ITERATOR_DECL(vnet_iter);
975
976 ip6_maxfrags = IP6_MAXFRAGS;
977 VNET_LIST_RLOCK_NOSLEEP();
978 VNET_FOREACH(vnet_iter) {
979 CURVNET_SET(vnet_iter);
980 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS;
981 frag6_set_bucketsize();
982 CURVNET_RESTORE();
983 }
984 VNET_LIST_RUNLOCK_NOSLEEP();
985 }
986
987 /*
988 * Initialise reassembly queue and fragment identifier.
989 */
990 void
991 frag6_init(void)
992 {
993 uint32_t bucket;
994
995 V_ip6_maxfragpackets = IP6_MAXFRAGPACKETS;
996 frag6_set_bucketsize();
997 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
998 TAILQ_INIT(IP6QB_HEAD(bucket));
999 mtx_init(&V_ip6qb[bucket].lock, "ip6qb", NULL, MTX_DEF);
1000 V_ip6qb[bucket].count = 0;
1001 }
1002 V_ip6qb_hashseed = arc4random();
1003 V_ip6_maxfragsperpacket = 64;
1004 #ifdef VIMAGE
1005 V_frag6_on = true;
1006 #endif
1007 if (!IS_DEFAULT_VNET(curvnet))
1008 return;
1009
1010 ip6_maxfrags = IP6_MAXFRAGS;
1011 EVENTHANDLER_REGISTER(nmbclusters_change,
1012 frag6_change, NULL, EVENTHANDLER_PRI_ANY);
1013 }
1014
1015 /*
1016 * Drain off all datagram fragments.
1017 */
1018 static void
1019 frag6_drain_one(void)
1020 {
1021 struct ip6q *q6;
1022 uint32_t bucket;
1023
1024 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
1025 IP6QB_LOCK(bucket);
1026 while ((q6 = TAILQ_FIRST(IP6QB_HEAD(bucket))) != NULL) {
1027 IP6STAT_INC(ip6s_fragdropped);
1028 /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
1029 frag6_freef(q6, bucket);
1030 }
1031 IP6QB_UNLOCK(bucket);
1032 }
1033 }
1034
1035 void
1036 frag6_drain(void)
1037 {
1038 VNET_ITERATOR_DECL(vnet_iter);
1039
1040 VNET_LIST_RLOCK_NOSLEEP();
1041 VNET_FOREACH(vnet_iter) {
1042 CURVNET_SET(vnet_iter);
1043 frag6_drain_one();
1044 CURVNET_RESTORE();
1045 }
1046 VNET_LIST_RUNLOCK_NOSLEEP();
1047 }
1048
1049 #ifdef VIMAGE
1050 /*
1051 * Clear up IPv6 reassembly structures.
1052 */
1053 void
1054 frag6_destroy(void)
1055 {
1056 uint32_t bucket;
1057
1058 frag6_drain_one();
1059 V_frag6_on = false;
1060 for (bucket = 0; bucket < IP6REASS_NHASH; bucket++) {
1061 KASSERT(V_ip6qb[bucket].count == 0,
1062 ("%s: V_ip6qb[%d] (%p) count not 0 (%d)", __func__,
1063 bucket, &V_ip6qb[bucket], V_ip6qb[bucket].count));
1064 mtx_destroy(&V_ip6qb[bucket].lock);
1065 }
1066 }
1067 #endif
Cache object: e06eba971e396c6dd730520a498fa399
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