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/if_private.h> 55 #include <net/rss_config.h> 56 #include <net/netisr.h> 57 #include <net/vnet.h> 58 59 #include <netinet/in.h> 60 #include <netinet/ip.h> 61 #include <netinet/ip_var.h> 62 #include <netinet/in_rss.h> 63 #ifdef MAC 64 #include <security/mac/mac_framework.h> 65 #endif 66 67 SYSCTL_DECL(_net_inet_ip); 68 69 /* 70 * Reassembly headers are stored in hash buckets. 71 */ 72 #define IPREASS_NHASH_LOG2 10 73 #define IPREASS_NHASH (1 << IPREASS_NHASH_LOG2) 74 #define IPREASS_HMASK (V_ipq_hashsize - 1) 75 76 struct ipqbucket { 77 TAILQ_HEAD(ipqhead, ipq) head; 78 struct mtx lock; 79 struct callout timer; 80 #ifdef VIMAGE 81 struct vnet *vnet; 82 #endif 83 int count; 84 }; 85 86 VNET_DEFINE_STATIC(struct ipqbucket *, ipq); 87 #define V_ipq VNET(ipq) 88 VNET_DEFINE_STATIC(uint32_t, ipq_hashseed); 89 #define V_ipq_hashseed VNET(ipq_hashseed) 90 VNET_DEFINE_STATIC(uint32_t, ipq_hashsize); 91 #define V_ipq_hashsize VNET(ipq_hashsize) 92 93 #define IPQ_LOCK(i) mtx_lock(&V_ipq[i].lock) 94 #define IPQ_TRYLOCK(i) mtx_trylock(&V_ipq[i].lock) 95 #define IPQ_UNLOCK(i) mtx_unlock(&V_ipq[i].lock) 96 #define IPQ_LOCK_ASSERT(i) mtx_assert(&V_ipq[i].lock, MA_OWNED) 97 #define IPQ_BUCKET_LOCK_ASSERT(b) mtx_assert(&(b)->lock, MA_OWNED) 98 99 VNET_DEFINE_STATIC(int, ipreass_maxbucketsize); 100 #define V_ipreass_maxbucketsize VNET(ipreass_maxbucketsize) 101 102 void ipreass_init(void); 103 void ipreass_vnet_init(void); 104 #ifdef VIMAGE 105 void ipreass_destroy(void); 106 #endif 107 static int sysctl_maxfragpackets(SYSCTL_HANDLER_ARGS); 108 static int sysctl_maxfragbucketsize(SYSCTL_HANDLER_ARGS); 109 static int sysctl_fragttl(SYSCTL_HANDLER_ARGS); 110 static void ipreass_zone_change(void *); 111 static void ipreass_drain_tomax(void); 112 static void ipq_free(struct ipqbucket *, struct ipq *); 113 static struct ipq * ipq_reuse(int); 114 static void ipreass_callout(void *); 115 static void ipreass_reschedule(struct ipqbucket *); 116 117 static inline void 118 ipq_timeout(struct ipqbucket *bucket, struct ipq *fp) 119 { 120 121 IPSTAT_ADD(ips_fragtimeout, fp->ipq_nfrags); 122 ipq_free(bucket, fp); 123 } 124 125 static inline void 126 ipq_drop(struct ipqbucket *bucket, struct ipq *fp) 127 { 128 129 IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags); 130 ipq_free(bucket, fp); 131 ipreass_reschedule(bucket); 132 } 133 134 /* 135 * By default, limit the number of IP fragments across all reassembly 136 * queues to 1/32 of the total number of mbuf clusters. 137 * 138 * Limit the total number of reassembly queues per VNET to the 139 * IP fragment limit, but ensure the limit will not allow any bucket 140 * to grow above 100 items. (The bucket limit is 141 * IP_MAXFRAGPACKETS / (V_ipq_hashsize / 2), so the 50 is the correct 142 * multiplier to reach a 100-item limit.) 143 * The 100-item limit was chosen as brief testing seems to show that 144 * this produces "reasonable" performance on some subset of systems 145 * under DoS attack. 146 */ 147 #define IP_MAXFRAGS (nmbclusters / 32) 148 #define IP_MAXFRAGPACKETS (imin(IP_MAXFRAGS, V_ipq_hashsize * 50)) 149 150 static int maxfrags; 151 static u_int __exclusive_cache_line nfrags; 152 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfrags, CTLFLAG_RW, 153 &maxfrags, 0, 154 "Maximum number of IPv4 fragments allowed across all reassembly queues"); 155 SYSCTL_UINT(_net_inet_ip, OID_AUTO, curfrags, CTLFLAG_RD, 156 &nfrags, 0, 157 "Current number of IPv4 fragments across all reassembly queues"); 158 159 VNET_DEFINE_STATIC(uma_zone_t, ipq_zone); 160 #define V_ipq_zone VNET(ipq_zone) 161 162 SYSCTL_UINT(_net_inet_ip, OID_AUTO, reass_hashsize, 163 CTLFLAG_VNET | CTLFLAG_RDTUN, &VNET_NAME(ipq_hashsize), 0, 164 "Size of IP fragment reassembly hashtable"); 165 166 SYSCTL_PROC(_net_inet_ip, OID_AUTO, maxfragpackets, 167 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 168 NULL, 0, sysctl_maxfragpackets, "I", 169 "Maximum number of IPv4 fragment reassembly queue entries"); 170 SYSCTL_UMA_CUR(_net_inet_ip, OID_AUTO, fragpackets, CTLFLAG_VNET, 171 &VNET_NAME(ipq_zone), 172 "Current number of IPv4 fragment reassembly queue entries"); 173 174 VNET_DEFINE_STATIC(int, noreass); 175 #define V_noreass VNET(noreass) 176 177 VNET_DEFINE_STATIC(int, maxfragsperpacket); 178 #define V_maxfragsperpacket VNET(maxfragsperpacket) 179 SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_VNET | CTLFLAG_RW, 180 &VNET_NAME(maxfragsperpacket), 0, 181 "Maximum number of IPv4 fragments allowed per packet"); 182 SYSCTL_PROC(_net_inet_ip, OID_AUTO, maxfragbucketsize, 183 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_MPSAFE | CTLFLAG_RW, NULL, 0, 184 sysctl_maxfragbucketsize, "I", 185 "Maximum number of IPv4 fragment reassembly queue entries per bucket"); 186 187 VNET_DEFINE_STATIC(u_int, ipfragttl) = 30; 188 #define V_ipfragttl VNET(ipfragttl) 189 SYSCTL_PROC(_net_inet_ip, OID_AUTO, fragttl, CTLTYPE_INT | CTLFLAG_RW | 190 CTLFLAG_MPSAFE | CTLFLAG_VNET, NULL, 0, sysctl_fragttl, "IU", 191 "IP fragment life time on reassembly queue (seconds)"); 192 193 /* 194 * Take incoming datagram fragment and try to reassemble it into 195 * whole datagram. If the argument is the first fragment or one 196 * in between the function will return NULL and store the mbuf 197 * in the fragment chain. If the argument is the last fragment 198 * the packet will be reassembled and the pointer to the new 199 * mbuf returned for further processing. Only m_tags attached 200 * to the first packet/fragment are preserved. 201 * The IP header is *NOT* adjusted out of iplen. 202 */ 203 #define M_IP_FRAG M_PROTO9 204 struct mbuf * 205 ip_reass(struct mbuf *m) 206 { 207 struct ip *ip; 208 struct mbuf *p, *q, *nq, *t; 209 struct ipq *fp; 210 struct ifnet *srcifp; 211 struct ipqhead *head; 212 int i, hlen, next, tmpmax; 213 u_int8_t ecn, ecn0; 214 uint32_t hash, hashkey[3]; 215 #ifdef RSS 216 uint32_t rss_hash, rss_type; 217 #endif 218 219 /* 220 * If no reassembling or maxfragsperpacket are 0, 221 * never accept fragments. 222 * Also, drop packet if it would exceed the maximum 223 * number of fragments. 224 */ 225 tmpmax = maxfrags; 226 if (V_noreass == 1 || V_maxfragsperpacket == 0 || 227 (tmpmax >= 0 && atomic_load_int(&nfrags) >= (u_int)tmpmax)) { 228 IPSTAT_INC(ips_fragments); 229 IPSTAT_INC(ips_fragdropped); 230 m_freem(m); 231 return (NULL); 232 } 233 234 ip = mtod(m, struct ip *); 235 hlen = ip->ip_hl << 2; 236 237 /* 238 * Adjust ip_len to not reflect header, 239 * convert offset of this to bytes. 240 */ 241 ip->ip_len = htons(ntohs(ip->ip_len) - hlen); 242 /* 243 * Make sure that fragments have a data length 244 * that's a non-zero multiple of 8 bytes, unless 245 * this is the last fragment. 246 */ 247 if (ip->ip_len == htons(0) || 248 ((ip->ip_off & htons(IP_MF)) && (ntohs(ip->ip_len) & 0x7) != 0)) { 249 IPSTAT_INC(ips_toosmall); /* XXX */ 250 IPSTAT_INC(ips_fragdropped); 251 m_freem(m); 252 return (NULL); 253 } 254 if (ip->ip_off & htons(IP_MF)) 255 m->m_flags |= M_IP_FRAG; 256 else 257 m->m_flags &= ~M_IP_FRAG; 258 ip->ip_off = htons(ntohs(ip->ip_off) << 3); 259 260 /* 261 * Make sure the fragment lies within a packet of valid size. 262 */ 263 if (ntohs(ip->ip_len) + ntohs(ip->ip_off) > IP_MAXPACKET) { 264 IPSTAT_INC(ips_toolong); 265 IPSTAT_INC(ips_fragdropped); 266 m_freem(m); 267 return (NULL); 268 } 269 270 /* 271 * Store receive network interface pointer for later. 272 */ 273 srcifp = m->m_pkthdr.rcvif; 274 275 /* 276 * Attempt reassembly; if it succeeds, proceed. 277 * ip_reass() will return a different mbuf. 278 */ 279 IPSTAT_INC(ips_fragments); 280 m->m_pkthdr.PH_loc.ptr = ip; 281 282 /* 283 * Presence of header sizes in mbufs 284 * would confuse code below. 285 */ 286 m->m_data += hlen; 287 m->m_len -= hlen; 288 289 hashkey[0] = ip->ip_src.s_addr; 290 hashkey[1] = ip->ip_dst.s_addr; 291 hashkey[2] = (uint32_t)ip->ip_p << 16; 292 hashkey[2] += ip->ip_id; 293 hash = jenkins_hash32(hashkey, nitems(hashkey), V_ipq_hashseed); 294 hash &= IPREASS_HMASK; 295 head = &V_ipq[hash].head; 296 IPQ_LOCK(hash); 297 298 /* 299 * Look for queue of fragments 300 * of this datagram. 301 */ 302 TAILQ_FOREACH(fp, head, ipq_list) 303 if (ip->ip_id == fp->ipq_id && 304 ip->ip_src.s_addr == fp->ipq_src.s_addr && 305 ip->ip_dst.s_addr == fp->ipq_dst.s_addr && 306 #ifdef MAC 307 mac_ipq_match(m, fp) && 308 #endif 309 ip->ip_p == fp->ipq_p) 310 break; 311 /* 312 * If first fragment to arrive, create a reassembly queue. 313 */ 314 if (fp == NULL) { 315 if (V_ipq[hash].count < V_ipreass_maxbucketsize) 316 fp = uma_zalloc(V_ipq_zone, M_NOWAIT); 317 if (fp == NULL) 318 fp = ipq_reuse(hash); 319 if (fp == NULL) 320 goto dropfrag; 321 #ifdef MAC 322 if (mac_ipq_init(fp, M_NOWAIT) != 0) { 323 uma_zfree(V_ipq_zone, fp); 324 fp = NULL; 325 goto dropfrag; 326 } 327 mac_ipq_create(m, fp); 328 #endif 329 TAILQ_INSERT_HEAD(head, fp, ipq_list); 330 V_ipq[hash].count++; 331 fp->ipq_nfrags = 1; 332 atomic_add_int(&nfrags, 1); 333 fp->ipq_expire = time_uptime + V_ipfragttl; 334 fp->ipq_p = ip->ip_p; 335 fp->ipq_id = ip->ip_id; 336 fp->ipq_src = ip->ip_src; 337 fp->ipq_dst = ip->ip_dst; 338 fp->ipq_frags = m; 339 if (m->m_flags & M_IP_FRAG) 340 fp->ipq_maxoff = -1; 341 else 342 fp->ipq_maxoff = ntohs(ip->ip_off) + ntohs(ip->ip_len); 343 m->m_nextpkt = NULL; 344 if (fp == TAILQ_LAST(head, ipqhead)) 345 callout_reset_sbt(&V_ipq[hash].timer, 346 SBT_1S * V_ipfragttl, SBT_1S, ipreass_callout, 347 &V_ipq[hash], 0); 348 else 349 MPASS(callout_active(&V_ipq[hash].timer)); 350 goto done; 351 } else { 352 /* 353 * If we already saw the last fragment, make sure 354 * this fragment's offset looks sane. Otherwise, if 355 * this is the last fragment, record its endpoint. 356 */ 357 if (fp->ipq_maxoff > 0) { 358 i = ntohs(ip->ip_off) + ntohs(ip->ip_len); 359 if (((m->m_flags & M_IP_FRAG) && i >= fp->ipq_maxoff) || 360 ((m->m_flags & M_IP_FRAG) == 0 && 361 i != fp->ipq_maxoff)) { 362 fp = NULL; 363 goto dropfrag; 364 } 365 } else if ((m->m_flags & M_IP_FRAG) == 0) 366 fp->ipq_maxoff = ntohs(ip->ip_off) + ntohs(ip->ip_len); 367 fp->ipq_nfrags++; 368 atomic_add_int(&nfrags, 1); 369 #ifdef MAC 370 mac_ipq_update(m, fp); 371 #endif 372 } 373 374 #define GETIP(m) ((struct ip*)((m)->m_pkthdr.PH_loc.ptr)) 375 376 /* 377 * Handle ECN by comparing this segment with the first one; 378 * if CE is set, do not lose CE. 379 * drop if CE and not-ECT are mixed for the same packet. 380 */ 381 ecn = ip->ip_tos & IPTOS_ECN_MASK; 382 ecn0 = GETIP(fp->ipq_frags)->ip_tos & IPTOS_ECN_MASK; 383 if (ecn == IPTOS_ECN_CE) { 384 if (ecn0 == IPTOS_ECN_NOTECT) 385 goto dropfrag; 386 if (ecn0 != IPTOS_ECN_CE) 387 GETIP(fp->ipq_frags)->ip_tos |= IPTOS_ECN_CE; 388 } 389 if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) 390 goto dropfrag; 391 392 /* 393 * Find a segment which begins after this one does. 394 */ 395 for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) 396 if (ntohs(GETIP(q)->ip_off) > ntohs(ip->ip_off)) 397 break; 398 399 /* 400 * If there is a preceding segment, it may provide some of 401 * our data already. If so, drop the data from the incoming 402 * segment. If it provides all of our data, drop us, otherwise 403 * stick new segment in the proper place. 404 * 405 * If some of the data is dropped from the preceding 406 * segment, then it's checksum is invalidated. 407 */ 408 if (p) { 409 i = ntohs(GETIP(p)->ip_off) + ntohs(GETIP(p)->ip_len) - 410 ntohs(ip->ip_off); 411 if (i > 0) { 412 if (i >= ntohs(ip->ip_len)) 413 goto dropfrag; 414 m_adj(m, i); 415 m->m_pkthdr.csum_flags = 0; 416 ip->ip_off = htons(ntohs(ip->ip_off) + i); 417 ip->ip_len = htons(ntohs(ip->ip_len) - i); 418 } 419 m->m_nextpkt = p->m_nextpkt; 420 p->m_nextpkt = m; 421 } else { 422 m->m_nextpkt = fp->ipq_frags; 423 fp->ipq_frags = m; 424 } 425 426 /* 427 * While we overlap succeeding segments trim them or, 428 * if they are completely covered, dequeue them. 429 */ 430 for (; q != NULL && ntohs(ip->ip_off) + ntohs(ip->ip_len) > 431 ntohs(GETIP(q)->ip_off); q = nq) { 432 i = (ntohs(ip->ip_off) + ntohs(ip->ip_len)) - 433 ntohs(GETIP(q)->ip_off); 434 if (i < ntohs(GETIP(q)->ip_len)) { 435 GETIP(q)->ip_len = htons(ntohs(GETIP(q)->ip_len) - i); 436 GETIP(q)->ip_off = htons(ntohs(GETIP(q)->ip_off) + i); 437 m_adj(q, i); 438 q->m_pkthdr.csum_flags = 0; 439 break; 440 } 441 nq = q->m_nextpkt; 442 m->m_nextpkt = nq; 443 IPSTAT_INC(ips_fragdropped); 444 fp->ipq_nfrags--; 445 atomic_subtract_int(&nfrags, 1); 446 m_freem(q); 447 } 448 449 /* 450 * Check for complete reassembly and perform frag per packet 451 * limiting. 452 * 453 * Frag limiting is performed here so that the nth frag has 454 * a chance to complete the packet before we drop the packet. 455 * As a result, n+1 frags are actually allowed per packet, but 456 * only n will ever be stored. (n = maxfragsperpacket.) 457 * 458 */ 459 next = 0; 460 for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) { 461 if (ntohs(GETIP(q)->ip_off) != next) { 462 if (fp->ipq_nfrags > V_maxfragsperpacket) 463 ipq_drop(&V_ipq[hash], fp); 464 goto done; 465 } 466 next += ntohs(GETIP(q)->ip_len); 467 } 468 /* Make sure the last packet didn't have the IP_MF flag */ 469 if (p->m_flags & M_IP_FRAG) { 470 if (fp->ipq_nfrags > V_maxfragsperpacket) 471 ipq_drop(&V_ipq[hash], fp); 472 goto done; 473 } 474 475 /* 476 * Reassembly is complete. Make sure the packet is a sane size. 477 */ 478 q = fp->ipq_frags; 479 ip = GETIP(q); 480 if (next + (ip->ip_hl << 2) > IP_MAXPACKET) { 481 IPSTAT_INC(ips_toolong); 482 ipq_drop(&V_ipq[hash], fp); 483 goto done; 484 } 485 486 /* 487 * Concatenate fragments. 488 */ 489 m = q; 490 t = m->m_next; 491 m->m_next = NULL; 492 m_cat(m, t); 493 nq = q->m_nextpkt; 494 q->m_nextpkt = NULL; 495 for (q = nq; q != NULL; q = nq) { 496 nq = q->m_nextpkt; 497 q->m_nextpkt = NULL; 498 m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags; 499 m->m_pkthdr.csum_data += q->m_pkthdr.csum_data; 500 m_demote_pkthdr(q); 501 m_cat(m, q); 502 } 503 /* 504 * In order to do checksumming faster we do 'end-around carry' here 505 * (and not in for{} loop), though it implies we are not going to 506 * reassemble more than 64k fragments. 507 */ 508 while (m->m_pkthdr.csum_data & 0xffff0000) 509 m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) + 510 (m->m_pkthdr.csum_data >> 16); 511 atomic_subtract_int(&nfrags, fp->ipq_nfrags); 512 #ifdef MAC 513 mac_ipq_reassemble(fp, m); 514 mac_ipq_destroy(fp); 515 #endif 516 517 /* 518 * Create header for new ip packet by modifying header of first 519 * packet; dequeue and discard fragment reassembly header. 520 * Make header visible. 521 */ 522 ip->ip_len = htons((ip->ip_hl << 2) + next); 523 ip->ip_src = fp->ipq_src; 524 ip->ip_dst = fp->ipq_dst; 525 TAILQ_REMOVE(head, fp, ipq_list); 526 V_ipq[hash].count--; 527 uma_zfree(V_ipq_zone, fp); 528 m->m_len += (ip->ip_hl << 2); 529 m->m_data -= (ip->ip_hl << 2); 530 /* some debugging cruft by sklower, below, will go away soon */ 531 if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */ 532 m_fixhdr(m); 533 /* set valid receive interface pointer */ 534 m->m_pkthdr.rcvif = srcifp; 535 } 536 IPSTAT_INC(ips_reassembled); 537 ipreass_reschedule(&V_ipq[hash]); 538 IPQ_UNLOCK(hash); 539 540 #ifdef RSS 541 /* 542 * Query the RSS layer for the flowid / flowtype for the 543 * mbuf payload. 544 * 545 * For now, just assume we have to calculate a new one. 546 * Later on we should check to see if the assigned flowid matches 547 * what RSS wants for the given IP protocol and if so, just keep it. 548 * 549 * We then queue into the relevant netisr so it can be dispatched 550 * to the correct CPU. 551 * 552 * Note - this may return 1, which means the flowid in the mbuf 553 * is correct for the configured RSS hash types and can be used. 554 */ 555 if (rss_mbuf_software_hash_v4(m, 0, &rss_hash, &rss_type) == 0) { 556 m->m_pkthdr.flowid = rss_hash; 557 M_HASHTYPE_SET(m, rss_type); 558 } 559 560 /* 561 * Queue/dispatch for reprocessing. 562 * 563 * Note: this is much slower than just handling the frame in the 564 * current receive context. It's likely worth investigating 565 * why this is. 566 */ 567 netisr_dispatch(NETISR_IP_DIRECT, m); 568 return (NULL); 569 #endif 570 571 /* Handle in-line */ 572 return (m); 573 574 dropfrag: 575 IPSTAT_INC(ips_fragdropped); 576 if (fp != NULL) { 577 fp->ipq_nfrags--; 578 atomic_subtract_int(&nfrags, 1); 579 } 580 m_freem(m); 581 done: 582 IPQ_UNLOCK(hash); 583 return (NULL); 584 585 #undef GETIP 586 } 587 588 /* 589 * Timer expired on a bucket. 590 * There should be at least one ipq to be timed out. 591 */ 592 static void 593 ipreass_callout(void *arg) 594 { 595 struct ipqbucket *bucket = arg; 596 struct ipq *fp; 597 598 IPQ_BUCKET_LOCK_ASSERT(bucket); 599 MPASS(atomic_load_int(&nfrags) > 0); 600 601 CURVNET_SET(bucket->vnet); 602 fp = TAILQ_LAST(&bucket->head, ipqhead); 603 KASSERT(fp != NULL && fp->ipq_expire <= time_uptime, 604 ("%s: stray callout on bucket %p, %ju < %ju", __func__, bucket, 605 fp ? (uintmax_t)fp->ipq_expire : 0, (uintmax_t)time_uptime)); 606 607 while (fp != NULL && fp->ipq_expire <= time_uptime) { 608 ipq_timeout(bucket, fp); 609 fp = TAILQ_LAST(&bucket->head, ipqhead); 610 } 611 ipreass_reschedule(bucket); 612 CURVNET_RESTORE(); 613 } 614 615 static void 616 ipreass_reschedule(struct ipqbucket *bucket) 617 { 618 struct ipq *fp; 619 620 IPQ_BUCKET_LOCK_ASSERT(bucket); 621 622 if ((fp = TAILQ_LAST(&bucket->head, ipqhead)) != NULL) { 623 time_t t; 624 625 /* Protect against time_uptime tick. */ 626 t = fp->ipq_expire - time_uptime; 627 t = (t > 0) ? t : 1; 628 callout_reset_sbt(&bucket->timer, SBT_1S * t, SBT_1S, 629 ipreass_callout, bucket, 0); 630 } else 631 callout_stop(&bucket->timer); 632 } 633 634 static void 635 ipreass_drain_vnet(void) 636 { 637 u_int dropped = 0; 638 639 for (int i = 0; i < V_ipq_hashsize; i++) { 640 bool resched; 641 642 IPQ_LOCK(i); 643 resched = !TAILQ_EMPTY(&V_ipq[i].head); 644 while(!TAILQ_EMPTY(&V_ipq[i].head)) { 645 struct ipq *fp = TAILQ_FIRST(&V_ipq[i].head); 646 647 dropped += fp->ipq_nfrags; 648 ipq_free(&V_ipq[i], fp); 649 } 650 if (resched) 651 ipreass_reschedule(&V_ipq[i]); 652 KASSERT(V_ipq[i].count == 0, 653 ("%s: V_ipq[%d] count %d (V_ipq=%p)", __func__, i, 654 V_ipq[i].count, V_ipq)); 655 IPQ_UNLOCK(i); 656 } 657 IPSTAT_ADD(ips_fragdropped, dropped); 658 } 659 660 /* 661 * Drain off all datagram fragments. 662 */ 663 static void 664 ipreass_drain(void) 665 { 666 VNET_ITERATOR_DECL(vnet_iter); 667 668 VNET_FOREACH(vnet_iter) { 669 CURVNET_SET(vnet_iter); 670 ipreass_drain_vnet(); 671 CURVNET_RESTORE(); 672 } 673 } 674 675 676 /* 677 * Initialize IP reassembly structures. 678 */ 679 MALLOC_DEFINE(M_IPREASS_HASH, "IP reass", "IP packet reassembly hash headers"); 680 void 681 ipreass_vnet_init(void) 682 { 683 int max; 684 685 V_ipq_hashsize = IPREASS_NHASH; 686 TUNABLE_INT_FETCH("net.inet.ip.reass_hashsize", &V_ipq_hashsize); 687 V_ipq = malloc(sizeof(struct ipqbucket) * V_ipq_hashsize, 688 M_IPREASS_HASH, M_WAITOK); 689 690 for (int i = 0; i < V_ipq_hashsize; i++) { 691 TAILQ_INIT(&V_ipq[i].head); 692 mtx_init(&V_ipq[i].lock, "IP reassembly", NULL, 693 MTX_DEF | MTX_DUPOK | MTX_NEW); 694 callout_init_mtx(&V_ipq[i].timer, &V_ipq[i].lock, 0); 695 V_ipq[i].count = 0; 696 #ifdef VIMAGE 697 V_ipq[i].vnet = curvnet; 698 #endif 699 } 700 V_ipq_hashseed = arc4random(); 701 V_maxfragsperpacket = 16; 702 V_ipq_zone = uma_zcreate("ipq", sizeof(struct ipq), NULL, NULL, NULL, 703 NULL, UMA_ALIGN_PTR, 0); 704 max = IP_MAXFRAGPACKETS; 705 max = uma_zone_set_max(V_ipq_zone, max); 706 V_ipreass_maxbucketsize = imax(max / (V_ipq_hashsize / 2), 1); 707 } 708 709 void 710 ipreass_init(void) 711 { 712 713 maxfrags = IP_MAXFRAGS; 714 EVENTHANDLER_REGISTER(nmbclusters_change, ipreass_zone_change, 715 NULL, EVENTHANDLER_PRI_ANY); 716 EVENTHANDLER_REGISTER(vm_lowmem, ipreass_drain, NULL, 717 LOWMEM_PRI_DEFAULT); 718 EVENTHANDLER_REGISTER(mbuf_lowmem, ipreass_drain, NULL, 719 LOWMEM_PRI_DEFAULT); 720 } 721 722 /* 723 * Drain off all datagram fragments belonging to 724 * the given network interface. 725 */ 726 static void 727 ipreass_cleanup(void *arg __unused, struct ifnet *ifp) 728 { 729 struct ipq *fp, *temp; 730 struct mbuf *m; 731 int i; 732 733 KASSERT(ifp != NULL, ("%s: ifp is NULL", __func__)); 734 735 CURVNET_SET_QUIET(ifp->if_vnet); 736 737 /* 738 * Skip processing if IPv4 reassembly is not initialised or 739 * torn down by ipreass_destroy(). 740 */ 741 if (V_ipq_zone == NULL) { 742 CURVNET_RESTORE(); 743 return; 744 } 745 746 for (i = 0; i < V_ipq_hashsize; i++) { 747 IPQ_LOCK(i); 748 /* Scan fragment list. */ 749 TAILQ_FOREACH_SAFE(fp, &V_ipq[i].head, ipq_list, temp) { 750 for (m = fp->ipq_frags; m != NULL; m = m->m_nextpkt) { 751 /* clear no longer valid rcvif pointer */ 752 if (m->m_pkthdr.rcvif == ifp) 753 m->m_pkthdr.rcvif = NULL; 754 } 755 } 756 IPQ_UNLOCK(i); 757 } 758 CURVNET_RESTORE(); 759 } 760 EVENTHANDLER_DEFINE(ifnet_departure_event, ipreass_cleanup, NULL, 0); 761 762 #ifdef VIMAGE 763 /* 764 * Destroy IP reassembly structures. 765 */ 766 void 767 ipreass_destroy(void) 768 { 769 770 ipreass_drain_vnet(); 771 uma_zdestroy(V_ipq_zone); 772 V_ipq_zone = NULL; 773 for (int i = 0; i < V_ipq_hashsize; i++) 774 mtx_destroy(&V_ipq[i].lock); 775 free(V_ipq, M_IPREASS_HASH); 776 } 777 #endif 778 779 /* 780 * After maxnipq has been updated, propagate the change to UMA. The UMA zone 781 * max has slightly different semantics than the sysctl, for historical 782 * reasons. 783 */ 784 static void 785 ipreass_drain_tomax(void) 786 { 787 struct ipq *fp; 788 int target; 789 790 /* 791 * Make sure each bucket is under the new limit. If 792 * necessary, drop enough of the oldest elements from 793 * each bucket to get under the new limit. 794 */ 795 for (int i = 0; i < V_ipq_hashsize; i++) { 796 IPQ_LOCK(i); 797 while (V_ipq[i].count > V_ipreass_maxbucketsize && 798 (fp = TAILQ_LAST(&V_ipq[i].head, ipqhead)) != NULL) 799 ipq_timeout(&V_ipq[i], fp); 800 ipreass_reschedule(&V_ipq[i]); 801 IPQ_UNLOCK(i); 802 } 803 804 /* 805 * If we are over the maximum number of fragments, 806 * drain off enough to get down to the new limit, 807 * stripping off last elements on queues. Every 808 * run we strip the oldest element from each bucket. 809 */ 810 target = uma_zone_get_max(V_ipq_zone); 811 while (uma_zone_get_cur(V_ipq_zone) > target) { 812 for (int i = 0; i < V_ipq_hashsize; i++) { 813 IPQ_LOCK(i); 814 fp = TAILQ_LAST(&V_ipq[i].head, ipqhead); 815 if (fp != NULL) { 816 ipq_timeout(&V_ipq[i], fp); 817 ipreass_reschedule(&V_ipq[i]); 818 } 819 IPQ_UNLOCK(i); 820 } 821 } 822 } 823 824 static void 825 ipreass_zone_change(void *tag) 826 { 827 VNET_ITERATOR_DECL(vnet_iter); 828 int max; 829 830 maxfrags = IP_MAXFRAGS; 831 max = IP_MAXFRAGPACKETS; 832 VNET_LIST_RLOCK_NOSLEEP(); 833 VNET_FOREACH(vnet_iter) { 834 CURVNET_SET(vnet_iter); 835 max = uma_zone_set_max(V_ipq_zone, max); 836 V_ipreass_maxbucketsize = imax(max / (V_ipq_hashsize / 2), 1); 837 ipreass_drain_tomax(); 838 CURVNET_RESTORE(); 839 } 840 VNET_LIST_RUNLOCK_NOSLEEP(); 841 } 842 843 /* 844 * Change the limit on the UMA zone, or disable the fragment allocation 845 * at all. Since 0 and -1 is a special values here, we need our own handler, 846 * instead of sysctl_handle_uma_zone_max(). 847 */ 848 static int 849 sysctl_maxfragpackets(SYSCTL_HANDLER_ARGS) 850 { 851 int error, max; 852 853 if (V_noreass == 0) { 854 max = uma_zone_get_max(V_ipq_zone); 855 if (max == 0) 856 max = -1; 857 } else 858 max = 0; 859 error = sysctl_handle_int(oidp, &max, 0, req); 860 if (error || !req->newptr) 861 return (error); 862 if (max > 0) { 863 /* 864 * XXXRW: Might be a good idea to sanity check the argument 865 * and place an extreme upper bound. 866 */ 867 max = uma_zone_set_max(V_ipq_zone, max); 868 V_ipreass_maxbucketsize = imax(max / (V_ipq_hashsize / 2), 1); 869 ipreass_drain_tomax(); 870 V_noreass = 0; 871 } else if (max == 0) { 872 V_noreass = 1; 873 ipreass_drain(); 874 } else if (max == -1) { 875 V_noreass = 0; 876 uma_zone_set_max(V_ipq_zone, 0); 877 V_ipreass_maxbucketsize = INT_MAX; 878 } else 879 return (EINVAL); 880 return (0); 881 } 882 883 /* 884 * Seek for old fragment queue header that can be reused. Try to 885 * reuse a header from currently locked hash bucket. 886 */ 887 static struct ipq * 888 ipq_reuse(int start) 889 { 890 struct ipq *fp; 891 int bucket, i; 892 893 IPQ_LOCK_ASSERT(start); 894 895 for (i = 0; i < V_ipq_hashsize; i++) { 896 bucket = (start + i) % V_ipq_hashsize; 897 if (bucket != start && IPQ_TRYLOCK(bucket) == 0) 898 continue; 899 fp = TAILQ_LAST(&V_ipq[bucket].head, ipqhead); 900 if (fp) { 901 struct mbuf *m; 902 903 IPSTAT_ADD(ips_fragtimeout, fp->ipq_nfrags); 904 atomic_subtract_int(&nfrags, fp->ipq_nfrags); 905 while (fp->ipq_frags) { 906 m = fp->ipq_frags; 907 fp->ipq_frags = m->m_nextpkt; 908 m_freem(m); 909 } 910 TAILQ_REMOVE(&V_ipq[bucket].head, fp, ipq_list); 911 V_ipq[bucket].count--; 912 ipreass_reschedule(&V_ipq[bucket]); 913 if (bucket != start) 914 IPQ_UNLOCK(bucket); 915 break; 916 } 917 if (bucket != start) 918 IPQ_UNLOCK(bucket); 919 } 920 IPQ_LOCK_ASSERT(start); 921 return (fp); 922 } 923 924 /* 925 * Free a fragment reassembly header and all associated datagrams. 926 */ 927 static void 928 ipq_free(struct ipqbucket *bucket, struct ipq *fp) 929 { 930 struct mbuf *q; 931 932 atomic_subtract_int(&nfrags, fp->ipq_nfrags); 933 while (fp->ipq_frags) { 934 q = fp->ipq_frags; 935 fp->ipq_frags = q->m_nextpkt; 936 m_freem(q); 937 } 938 TAILQ_REMOVE(&bucket->head, fp, ipq_list); 939 bucket->count--; 940 uma_zfree(V_ipq_zone, fp); 941 } 942 943 /* 944 * Get or set the maximum number of reassembly queues per bucket. 945 */ 946 static int 947 sysctl_maxfragbucketsize(SYSCTL_HANDLER_ARGS) 948 { 949 int error, max; 950 951 max = V_ipreass_maxbucketsize; 952 error = sysctl_handle_int(oidp, &max, 0, req); 953 if (error || !req->newptr) 954 return (error); 955 if (max <= 0) 956 return (EINVAL); 957 V_ipreass_maxbucketsize = max; 958 ipreass_drain_tomax(); 959 return (0); 960 } 961 962 /* 963 * Get or set the IP fragment time to live. 964 */ 965 static int 966 sysctl_fragttl(SYSCTL_HANDLER_ARGS) 967 { 968 u_int ttl; 969 int error; 970 971 ttl = V_ipfragttl; 972 error = sysctl_handle_int(oidp, &ttl, 0, req); 973 if (error || !req->newptr) 974 return (error); 975 976 if (ttl < 1 || ttl > MAXTTL) 977 return (EINVAL); 978 979 atomic_store_int(&V_ipfragttl, ttl); 980 return (0); 981 } 982