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