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 * 3. 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("$FreeBSD$"); 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/eventhandler.h> 42 #include <sys/malloc.h> 43 #include <sys/mbuf.h> 44 #include <sys/socket.h> 45 #include <sys/socketvar.h> 46 #include <sys/sysctl.h> 47 #include <sys/syslog.h> 48 #include <sys/systm.h> 49 50 #include <vm/uma.h> 51 52 #include <net/if.h> 53 #include <net/if_var.h> 54 #include <net/route.h> 55 #include <net/vnet.h> 56 57 #include <netinet/in.h> 58 #include <netinet/in_pcb.h> 59 #include <netinet/in_systm.h> 60 #include <netinet/in_var.h> 61 #include <netinet/ip.h> 62 #include <netinet/ip_var.h> 63 #include <netinet/ip_options.h> 64 #include <netinet/ip6.h> 65 #include <netinet6/in6_pcb.h> 66 #include <netinet6/ip6_var.h> 67 #include <netinet6/nd6.h> 68 #include <netinet/tcp.h> 69 #include <netinet/tcp_fsm.h> 70 #include <netinet/tcp_seq.h> 71 #include <netinet/tcp_timer.h> 72 #include <netinet/tcp_var.h> 73 #include <netinet6/tcp6_var.h> 74 #include <netinet/tcpip.h> 75 #ifdef TCPDEBUG 76 #include <netinet/tcp_debug.h> 77 #endif /* TCPDEBUG */ 78 79 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0, 80 "TCP Segment Reassembly Queue"); 81 82 static int tcp_reass_maxseg = 0; 83 SYSCTL_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 87 static uma_zone_t tcp_reass_zone; 88 SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, 0, 89 &tcp_reass_zone, 90 "Global number of TCP Segments currently in Reassembly Queue"); 91 92 /* Initialize TCP reassembly queue */ 93 static void 94 tcp_reass_zone_change(void *tag) 95 { 96 97 /* Set the zone limit and read back the effective value. */ 98 tcp_reass_maxseg = nmbclusters / 16; 99 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, 100 tcp_reass_maxseg); 101 } 102 103 void 104 tcp_reass_global_init(void) 105 { 106 107 tcp_reass_maxseg = nmbclusters / 16; 108 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", 109 &tcp_reass_maxseg); 110 tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent), 111 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 112 /* Set the zone limit and read back the effective value. */ 113 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, 114 tcp_reass_maxseg); 115 EVENTHANDLER_REGISTER(nmbclusters_change, 116 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY); 117 } 118 119 void 120 tcp_reass_flush(struct tcpcb *tp) 121 { 122 struct tseg_qent *qe; 123 124 INP_WLOCK_ASSERT(tp->t_inpcb); 125 126 while ((qe = LIST_FIRST(&tp->t_segq)) != NULL) { 127 LIST_REMOVE(qe, tqe_q); 128 m_freem(qe->tqe_m); 129 uma_zfree(tcp_reass_zone, qe); 130 tp->t_segqlen--; 131 } 132 133 KASSERT((tp->t_segqlen == 0), 134 ("TCP reass queue %p segment count is %d instead of 0 after flush.", 135 tp, tp->t_segqlen)); 136 } 137 138 int 139 tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m) 140 { 141 struct tseg_qent *q; 142 struct tseg_qent *p = NULL; 143 struct tseg_qent *nq; 144 struct tseg_qent *te = NULL; 145 struct socket *so = tp->t_inpcb->inp_socket; 146 char *s = NULL; 147 int flags; 148 struct tseg_qent tqs; 149 150 INP_WLOCK_ASSERT(tp->t_inpcb); 151 152 /* 153 * XXX: tcp_reass() is rather inefficient with its data structures 154 * and should be rewritten (see NetBSD for optimizations). 155 */ 156 157 /* 158 * Call with th==NULL after become established to 159 * force pre-ESTABLISHED data up to user socket. 160 */ 161 if (th == NULL) 162 goto present; 163 164 /* 165 * Limit the number of segments that can be queued to reduce the 166 * potential for mbuf exhaustion. For best performance, we want to be 167 * able to queue a full window's worth of segments. The size of the 168 * socket receive buffer determines our advertised window and grows 169 * automatically when socket buffer autotuning is enabled. Use it as the 170 * basis for our queue limit. 171 * Always let the missing segment through which caused this queue. 172 * NB: Access to the socket buffer is left intentionally unlocked as we 173 * can tolerate stale information here. 174 * 175 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat 176 * should work but causes packets to be dropped when they shouldn't. 177 * Investigate why and re-evaluate the below limit after the behaviour 178 * is understood. 179 */ 180 if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) && 181 tp->t_segqlen >= (so->so_rcv.sb_hiwat / tp->t_maxseg) + 1) { 182 TCPSTAT_INC(tcps_rcvreassfull); 183 *tlenp = 0; 184 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { 185 log(LOG_DEBUG, "%s; %s: queue limit reached, " 186 "segment dropped\n", s, __func__); 187 free(s, M_TCPLOG); 188 } 189 m_freem(m); 190 return (0); 191 } 192 193 /* 194 * Allocate a new queue entry. If we can't, or hit the zone limit 195 * just drop the pkt. 196 * 197 * Use a temporary structure on the stack for the missing segment 198 * when the zone is exhausted. Otherwise we may get stuck. 199 */ 200 te = uma_zalloc(tcp_reass_zone, M_NOWAIT); 201 if (te == NULL) { 202 if (th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) { 203 TCPSTAT_INC(tcps_rcvmemdrop); 204 m_freem(m); 205 *tlenp = 0; 206 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, 207 NULL))) { 208 log(LOG_DEBUG, "%s; %s: global zone limit " 209 "reached, segment dropped\n", s, __func__); 210 free(s, M_TCPLOG); 211 } 212 return (0); 213 } else { 214 bzero(&tqs, sizeof(struct tseg_qent)); 215 te = &tqs; 216 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, 217 NULL))) { 218 log(LOG_DEBUG, 219 "%s; %s: global zone limit reached, using " 220 "stack for missing segment\n", s, __func__); 221 free(s, M_TCPLOG); 222 } 223 } 224 } 225 tp->t_segqlen++; 226 227 /* 228 * Find a segment which begins after this one does. 229 */ 230 LIST_FOREACH(q, &tp->t_segq, tqe_q) { 231 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq)) 232 break; 233 p = q; 234 } 235 236 /* 237 * If there is a preceding segment, it may provide some of 238 * our data already. If so, drop the data from the incoming 239 * segment. If it provides all of our data, drop us. 240 */ 241 if (p != NULL) { 242 int i; 243 /* conversion to int (in i) handles seq wraparound */ 244 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq; 245 if (i > 0) { 246 if (i >= *tlenp) { 247 TCPSTAT_INC(tcps_rcvduppack); 248 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 249 m_freem(m); 250 if (te != &tqs) 251 uma_zfree(tcp_reass_zone, te); 252 tp->t_segqlen--; 253 /* 254 * Try to present any queued data 255 * at the left window edge to the user. 256 * This is needed after the 3-WHS 257 * completes. 258 */ 259 goto present; /* ??? */ 260 } 261 m_adj(m, i); 262 *tlenp -= i; 263 th->th_seq += i; 264 } 265 } 266 tp->t_rcvoopack++; 267 TCPSTAT_INC(tcps_rcvoopack); 268 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); 269 270 /* 271 * While we overlap succeeding segments trim them or, 272 * if they are completely covered, dequeue them. 273 */ 274 while (q) { 275 int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq; 276 if (i <= 0) 277 break; 278 if (i < q->tqe_len) { 279 q->tqe_th->th_seq += i; 280 q->tqe_len -= i; 281 m_adj(q->tqe_m, i); 282 break; 283 } 284 285 nq = LIST_NEXT(q, tqe_q); 286 LIST_REMOVE(q, tqe_q); 287 m_freem(q->tqe_m); 288 uma_zfree(tcp_reass_zone, q); 289 tp->t_segqlen--; 290 q = nq; 291 } 292 293 /* Insert the new segment queue entry into place. */ 294 te->tqe_m = m; 295 te->tqe_th = th; 296 te->tqe_len = *tlenp; 297 298 if (p == NULL) { 299 LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q); 300 } else { 301 KASSERT(te != &tqs, ("%s: temporary stack based entry not " 302 "first element in queue", __func__)); 303 LIST_INSERT_AFTER(p, te, tqe_q); 304 } 305 306 present: 307 /* 308 * Present data to user, advancing rcv_nxt through 309 * completed sequence space. 310 */ 311 if (!TCPS_HAVEESTABLISHED(tp->t_state)) 312 return (0); 313 q = LIST_FIRST(&tp->t_segq); 314 if (!q || q->tqe_th->th_seq != tp->rcv_nxt) 315 return (0); 316 SOCKBUF_LOCK(&so->so_rcv); 317 do { 318 tp->rcv_nxt += q->tqe_len; 319 flags = q->tqe_th->th_flags & TH_FIN; 320 nq = LIST_NEXT(q, tqe_q); 321 LIST_REMOVE(q, tqe_q); 322 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 323 m_freem(q->tqe_m); 324 else 325 sbappendstream_locked(&so->so_rcv, q->tqe_m, 0); 326 if (q != &tqs) 327 uma_zfree(tcp_reass_zone, q); 328 tp->t_segqlen--; 329 q = nq; 330 } while (q && q->tqe_th->th_seq == tp->rcv_nxt); 331 sorwakeup_locked(so); 332 return (flags); 333 } 334