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