1/*- 2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 30 */ 31 32#include <sys/cdefs.h> 33__FBSDID("$FreeBSD: stable/10/sys/netinet/tcp_reass.c 337386 2018-08-06 17:46:28Z jtl $"); 34 35#include "opt_inet.h" 36#include "opt_inet6.h" 37#include "opt_tcpdebug.h" 38 39#include <sys/param.h> 40#include <sys/kernel.h> 41#include <sys/malloc.h> 42#include <sys/mbuf.h> 43#include <sys/socket.h> 44#include <sys/socketvar.h> 45#include <sys/sysctl.h> 46#include <sys/syslog.h> 47#include <sys/systm.h> 48 49#include <vm/uma.h> 50 51#include <net/if.h> 52#include <net/route.h> 53#include <net/vnet.h> 54 55#include <netinet/in.h> 56#include <netinet/in_pcb.h> 57#include <netinet/in_systm.h> 58#include <netinet/in_var.h> 59#include <netinet/ip.h> 60#include <netinet/ip_var.h> 61#include <netinet/ip_options.h> 62#include <netinet/ip6.h> 63#include <netinet6/in6_pcb.h> 64#include <netinet6/ip6_var.h> 65#include <netinet6/nd6.h> 66#include <netinet/tcp.h> 67#include <netinet/tcp_fsm.h> 68#include <netinet/tcp_seq.h> 69#include <netinet/tcp_timer.h> 70#include <netinet/tcp_var.h> 71#include <netinet6/tcp6_var.h> 72#include <netinet/tcpip.h> 73#ifdef TCPDEBUG 74#include <netinet/tcp_debug.h> 75#endif /* TCPDEBUG */ 76 77static int tcp_reass_sysctl_qsize(SYSCTL_HANDLER_ARGS); 78 79static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0, 80 "TCP Segment Reassembly Queue"); 81 82static int tcp_reass_maxseg = 0; 83SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN, 84 &tcp_reass_maxseg, 0, 85 "Global maximum number of TCP Segments in Reassembly Queue"); 86 87SYSCTL_PROC(_net_inet_tcp_reass, OID_AUTO, cursegments, 88 (CTLTYPE_INT | CTLFLAG_RD), NULL, 0, &tcp_reass_sysctl_qsize, "I", 89 "Global number of TCP Segments currently in Reassembly Queue"); 90 91static int tcp_reass_overflows = 0; 92SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, overflows, 93 CTLFLAG_RD, 94 &tcp_reass_overflows, 0, 95 "Global number of TCP Segment Reassembly Queue Overflows"); 96 97static uma_zone_t tcp_reass_zone; 98 99static u_int tcp_reass_maxqueuelen = 100; 100SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, maxqueuelen, CTLFLAG_RWTUN, 101 &tcp_reass_maxqueuelen, 0, 102 "Maximum number of TCP Segments per Reassembly Queue"); 103 104/* Initialize TCP reassembly queue */ 105static void 106tcp_reass_zone_change(void *tag) 107{ 108 109 /* Set the zone limit and read back the effective value. */ 110 tcp_reass_maxseg = nmbclusters / 16; 111 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, 112 tcp_reass_maxseg); 113} 114 115void 116tcp_reass_global_init(void) 117{ 118 119 tcp_reass_maxseg = nmbclusters / 16; 120 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", 121 &tcp_reass_maxseg); 122 tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent), 123 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 124 /* Set the zone limit and read back the effective value. */ 125 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, 126 tcp_reass_maxseg); 127 EVENTHANDLER_REGISTER(nmbclusters_change, 128 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY); 129} 130 131void 132tcp_reass_flush(struct tcpcb *tp) 133{ 134 struct tseg_qent *qe; 135 136 INP_WLOCK_ASSERT(tp->t_inpcb); 137 138 while ((qe = LIST_FIRST(&tp->t_segq)) != NULL) { 139 LIST_REMOVE(qe, tqe_q); 140 m_freem(qe->tqe_m); 141 uma_zfree(tcp_reass_zone, qe); 142 tp->t_segqlen--; 143 } 144 145 KASSERT((tp->t_segqlen == 0), 146 ("TCP reass queue %p segment count is %d instead of 0 after flush.", 147 tp, tp->t_segqlen)); 148} 149 150static int 151tcp_reass_sysctl_qsize(SYSCTL_HANDLER_ARGS) 152{ 153 int qsize; 154 155 qsize = uma_zone_get_cur(tcp_reass_zone); 156 return (sysctl_handle_int(oidp, &qsize, 0, req)); 157} 158 159int 160tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m) 161{ 162 struct tseg_qent *q; 163 struct tseg_qent *p = NULL; 164 struct tseg_qent *nq; 165 struct tseg_qent *te = NULL; 166 struct socket *so = tp->t_inpcb->inp_socket; 167 char *s = NULL; 168 int flags; 169 struct tseg_qent tqs; 170 171 INP_WLOCK_ASSERT(tp->t_inpcb); 172 173 /* 174 * XXX: tcp_reass() is rather inefficient with its data structures 175 * and should be rewritten (see NetBSD for optimizations). 176 */ 177 178 /* 179 * Call with th==NULL after become established to 180 * force pre-ESTABLISHED data up to user socket. 181 */ 182 if (th == NULL) 183 goto present; 184 185 /* 186 * Limit the number of segments that can be queued to reduce the 187 * potential for mbuf exhaustion. For best performance, we want to be 188 * able to queue a full window's worth of segments. The size of the 189 * socket receive buffer determines our advertised window and grows 190 * automatically when socket buffer autotuning is enabled. Use it as the 191 * basis for our queue limit. 192 * 193 * However, allow the user to specify a ceiling for the number of 194 * segments in each queue. 195 * 196 * Always let the missing segment through which caused this queue. 197 * NB: Access to the socket buffer is left intentionally unlocked as we 198 * can tolerate stale information here. 199 * 200 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat 201 * should work but causes packets to be dropped when they shouldn't. 202 * Investigate why and re-evaluate the below limit after the behaviour 203 * is understood. 204 */ 205 if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) && 206 tp->t_segqlen >= min((so->so_rcv.sb_hiwat / tp->t_maxseg) + 1, 207 tcp_reass_maxqueuelen)) { 208 tcp_reass_overflows++; 209 TCPSTAT_INC(tcps_rcvmemdrop); 210 m_freem(m); 211 *tlenp = 0; 212 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { 213 log(LOG_DEBUG, "%s; %s: queue limit reached, " 214 "segment dropped\n", s, __func__); 215 free(s, M_TCPLOG); 216 } 217 return (0); 218 } 219 220 /* 221 * Allocate a new queue entry. If we can't, or hit the zone limit 222 * just drop the pkt. 223 * 224 * Use a temporary structure on the stack for the missing segment 225 * when the zone is exhausted. Otherwise we may get stuck. 226 */ 227 te = uma_zalloc(tcp_reass_zone, M_NOWAIT); 228 if (te == NULL) { 229 if (th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) { 230 TCPSTAT_INC(tcps_rcvmemdrop); 231 m_freem(m); 232 *tlenp = 0; 233 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, 234 NULL))) { 235 log(LOG_DEBUG, "%s; %s: global zone limit " 236 "reached, segment dropped\n", s, __func__); 237 free(s, M_TCPLOG); 238 } 239 return (0); 240 } else { 241 bzero(&tqs, sizeof(struct tseg_qent)); 242 te = &tqs; 243 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, 244 NULL))) { 245 log(LOG_DEBUG, 246 "%s; %s: global zone limit reached, using " 247 "stack for missing segment\n", s, __func__); 248 free(s, M_TCPLOG); 249 } 250 } 251 } 252 tp->t_segqlen++; 253 254 /* 255 * Find a segment which begins after this one does. 256 */ 257 LIST_FOREACH(q, &tp->t_segq, tqe_q) { 258 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq)) 259 break; 260 p = q; 261 } 262 263 /* 264 * If there is a preceding segment, it may provide some of 265 * our data already. If so, drop the data from the incoming 266 * segment. If it provides all of our data, drop us. 267 */ 268 if (p != NULL) { 269 int i; 270 /* conversion to int (in i) handles seq wraparound */ 271 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq; 272 if (i > 0) { 273 if (i >= *tlenp) { 274 TCPSTAT_INC(tcps_rcvduppack); 275 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 276 m_freem(m); 277 if (te != &tqs) 278 uma_zfree(tcp_reass_zone, te); 279 tp->t_segqlen--; 280 /* 281 * Try to present any queued data 282 * at the left window edge to the user. 283 * This is needed after the 3-WHS 284 * completes. 285 */ 286 goto present; /* ??? */ 287 } 288 m_adj(m, i); 289 *tlenp -= i; 290 th->th_seq += i; 291 } 292 } 293 tp->t_rcvoopack++; 294 TCPSTAT_INC(tcps_rcvoopack); 295 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); 296 297 /* 298 * While we overlap succeeding segments trim them or, 299 * if they are completely covered, dequeue them. 300 */ 301 while (q) { 302 int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq; 303 if (i <= 0) 304 break; 305 if (i < q->tqe_len) { 306 q->tqe_th->th_seq += i; 307 q->tqe_len -= i; 308 m_adj(q->tqe_m, i); 309 break; 310 } 311 312 nq = LIST_NEXT(q, tqe_q); 313 LIST_REMOVE(q, tqe_q); 314 m_freem(q->tqe_m); 315 uma_zfree(tcp_reass_zone, q); 316 tp->t_segqlen--; 317 q = nq; 318 } 319 320 /* Insert the new segment queue entry into place. */ 321 te->tqe_m = m; 322 te->tqe_th = th; 323 te->tqe_len = *tlenp; 324 325 if (p == NULL) { 326 LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q); 327 } else { 328 KASSERT(te != &tqs, ("%s: temporary stack based entry not " 329 "first element in queue", __func__)); 330 LIST_INSERT_AFTER(p, te, tqe_q); 331 } 332 333present: 334 /* 335 * Present data to user, advancing rcv_nxt through 336 * completed sequence space. 337 */ 338 if (!TCPS_HAVEESTABLISHED(tp->t_state)) 339 return (0); 340 q = LIST_FIRST(&tp->t_segq); 341 if (!q || q->tqe_th->th_seq != tp->rcv_nxt) 342 return (0); 343 SOCKBUF_LOCK(&so->so_rcv); 344 do { 345 tp->rcv_nxt += q->tqe_len; 346 flags = q->tqe_th->th_flags & TH_FIN; 347 nq = LIST_NEXT(q, tqe_q); 348 LIST_REMOVE(q, tqe_q); 349 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 350 m_freem(q->tqe_m); 351 else 352 sbappendstream_locked(&so->so_rcv, q->tqe_m); 353 if (q != &tqs) 354 uma_zfree(tcp_reass_zone, q); 355 tp->t_segqlen--; 356 q = nq; 357 } while (q && q->tqe_th->th_seq == tp->rcv_nxt); 358 ND6_HINT(tp); 359 sorwakeup_locked(so); 360 return (flags); 361} 362