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