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("$FreeBSD$"); 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/if_var.h> 53 #include <net/route.h> 54 #include <net/vnet.h> 55 56 #include <netinet/in.h> 57 #include <netinet/in_pcb.h> 58 #include <netinet/in_systm.h> 59 #include <netinet/in_var.h> 60 #include <netinet/ip.h> 61 #include <netinet/ip_var.h> 62 #include <netinet/ip_options.h> 63 #include <netinet/ip6.h> 64 #include <netinet6/in6_pcb.h> 65 #include <netinet6/ip6_var.h> 66 #include <netinet6/nd6.h> 67 #include <netinet/tcp.h> 68 #include <netinet/tcp_fsm.h> 69 #include <netinet/tcp_seq.h> 70 #include <netinet/tcp_timer.h> 71 #include <netinet/tcp_var.h> 72 #include <netinet6/tcp6_var.h> 73 #include <netinet/tcpip.h> 74 #ifdef TCPDEBUG 75 #include <netinet/tcp_debug.h> 76 #endif /* TCPDEBUG */ 77 78 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0, 79 "TCP Segment Reassembly Queue"); 80 81 static int tcp_reass_maxseg = 0; 82 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN, 83 &tcp_reass_maxseg, 0, 84 "Global maximum number of TCP Segments in Reassembly Queue"); 85 86 static uma_zone_t tcp_reass_zone; 87 SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, 0, 88 &tcp_reass_zone, 89 "Global number of TCP Segments currently in Reassembly Queue"); 90 91 /* Initialize TCP reassembly queue */ 92 static void 93 tcp_reass_zone_change(void *tag) 94 { 95 96 /* Set the zone limit and read back the effective value. */ 97 tcp_reass_maxseg = nmbclusters / 16; 98 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, 99 tcp_reass_maxseg); 100 } 101 102 void 103 tcp_reass_global_init(void) 104 { 105 106 tcp_reass_maxseg = nmbclusters / 16; 107 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", 108 &tcp_reass_maxseg); 109 tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent), 110 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 111 /* Set the zone limit and read back the effective value. */ 112 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, 113 tcp_reass_maxseg); 114 EVENTHANDLER_REGISTER(nmbclusters_change, 115 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY); 116 } 117 118 void 119 tcp_reass_flush(struct tcpcb *tp) 120 { 121 struct tseg_qent *qe; 122 123 INP_WLOCK_ASSERT(tp->t_inpcb); 124 125 while ((qe = LIST_FIRST(&tp->t_segq)) != NULL) { 126 LIST_REMOVE(qe, tqe_q); 127 m_freem(qe->tqe_m); 128 uma_zfree(tcp_reass_zone, qe); 129 tp->t_segqlen--; 130 } 131 132 KASSERT((tp->t_segqlen == 0), 133 ("TCP reass queue %p segment count is %d instead of 0 after flush.", 134 tp, tp->t_segqlen)); 135 } 136 137 int 138 tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m) 139 { 140 struct tseg_qent *q; 141 struct tseg_qent *p = NULL; 142 struct tseg_qent *nq; 143 struct tseg_qent *te = NULL; 144 struct socket *so = tp->t_inpcb->inp_socket; 145 char *s = NULL; 146 int flags; 147 struct tseg_qent tqs; 148 149 INP_WLOCK_ASSERT(tp->t_inpcb); 150 151 /* 152 * XXX: tcp_reass() is rather inefficient with its data structures 153 * and should be rewritten (see NetBSD for optimizations). 154 */ 155 156 /* 157 * Call with th==NULL after become established to 158 * force pre-ESTABLISHED data up to user socket. 159 */ 160 if (th == NULL) 161 goto present; 162 163 /* 164 * Limit the number of segments that can be queued to reduce the 165 * potential for mbuf exhaustion. For best performance, we want to be 166 * able to queue a full window's worth of segments. The size of the 167 * socket receive buffer determines our advertised window and grows 168 * automatically when socket buffer autotuning is enabled. Use it as the 169 * basis for our queue limit. 170 * Always let the missing segment through which caused this queue. 171 * NB: Access to the socket buffer is left intentionally unlocked as we 172 * can tolerate stale information here. 173 * 174 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat 175 * should work but causes packets to be dropped when they shouldn't. 176 * Investigate why and re-evaluate the below limit after the behaviour 177 * is understood. 178 */ 179 if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) && 180 tp->t_segqlen >= (so->so_rcv.sb_hiwat / tp->t_maxseg) + 1) { 181 TCPSTAT_INC(tcps_rcvreassfull); 182 *tlenp = 0; 183 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { 184 log(LOG_DEBUG, "%s; %s: queue limit reached, " 185 "segment dropped\n", s, __func__); 186 free(s, M_TCPLOG); 187 } 188 m_freem(m); 189 return (0); 190 } 191 192 /* 193 * Allocate a new queue entry. If we can't, or hit the zone limit 194 * just drop the pkt. 195 * 196 * Use a temporary structure on the stack for the missing segment 197 * when the zone is exhausted. Otherwise we may get stuck. 198 */ 199 te = uma_zalloc(tcp_reass_zone, M_NOWAIT); 200 if (te == NULL) { 201 if (th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) { 202 TCPSTAT_INC(tcps_rcvmemdrop); 203 m_freem(m); 204 *tlenp = 0; 205 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, 206 NULL))) { 207 log(LOG_DEBUG, "%s; %s: global zone limit " 208 "reached, segment dropped\n", s, __func__); 209 free(s, M_TCPLOG); 210 } 211 return (0); 212 } else { 213 bzero(&tqs, sizeof(struct tseg_qent)); 214 te = &tqs; 215 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, 216 NULL))) { 217 log(LOG_DEBUG, 218 "%s; %s: global zone limit reached, using " 219 "stack for missing segment\n", s, __func__); 220 free(s, M_TCPLOG); 221 } 222 } 223 } 224 tp->t_segqlen++; 225 226 /* 227 * Find a segment which begins after this one does. 228 */ 229 LIST_FOREACH(q, &tp->t_segq, tqe_q) { 230 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq)) 231 break; 232 p = q; 233 } 234 235 /* 236 * If there is a preceding segment, it may provide some of 237 * our data already. If so, drop the data from the incoming 238 * segment. If it provides all of our data, drop us. 239 */ 240 if (p != NULL) { 241 int i; 242 /* conversion to int (in i) handles seq wraparound */ 243 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq; 244 if (i > 0) { 245 if (i >= *tlenp) { 246 TCPSTAT_INC(tcps_rcvduppack); 247 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 248 m_freem(m); 249 if (te != &tqs) 250 uma_zfree(tcp_reass_zone, te); 251 tp->t_segqlen--; 252 /* 253 * Try to present any queued data 254 * at the left window edge to the user. 255 * This is needed after the 3-WHS 256 * completes. 257 */ 258 goto present; /* ??? */ 259 } 260 m_adj(m, i); 261 *tlenp -= i; 262 th->th_seq += i; 263 } 264 } 265 tp->t_rcvoopack++; 266 TCPSTAT_INC(tcps_rcvoopack); 267 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); 268 269 /* 270 * While we overlap succeeding segments trim them or, 271 * if they are completely covered, dequeue them. 272 */ 273 while (q) { 274 int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq; 275 if (i <= 0) 276 break; 277 if (i < q->tqe_len) { 278 q->tqe_th->th_seq += i; 279 q->tqe_len -= i; 280 m_adj(q->tqe_m, i); 281 break; 282 } 283 284 nq = LIST_NEXT(q, tqe_q); 285 LIST_REMOVE(q, tqe_q); 286 m_freem(q->tqe_m); 287 uma_zfree(tcp_reass_zone, q); 288 tp->t_segqlen--; 289 q = nq; 290 } 291 292 /* Insert the new segment queue entry into place. */ 293 te->tqe_m = m; 294 te->tqe_th = th; 295 te->tqe_len = *tlenp; 296 297 if (p == NULL) { 298 LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q); 299 } else { 300 KASSERT(te != &tqs, ("%s: temporary stack based entry not " 301 "first element in queue", __func__)); 302 LIST_INSERT_AFTER(p, te, tqe_q); 303 } 304 305 present: 306 /* 307 * Present data to user, advancing rcv_nxt through 308 * completed sequence space. 309 */ 310 if (!TCPS_HAVEESTABLISHED(tp->t_state)) 311 return (0); 312 q = LIST_FIRST(&tp->t_segq); 313 if (!q || q->tqe_th->th_seq != tp->rcv_nxt) 314 return (0); 315 SOCKBUF_LOCK(&so->so_rcv); 316 do { 317 tp->rcv_nxt += q->tqe_len; 318 flags = q->tqe_th->th_flags & TH_FIN; 319 nq = LIST_NEXT(q, tqe_q); 320 LIST_REMOVE(q, tqe_q); 321 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 322 m_freem(q->tqe_m); 323 else 324 sbappendstream_locked(&so->so_rcv, q->tqe_m, 0); 325 if (q != &tqs) 326 uma_zfree(tcp_reass_zone, q); 327 tp->t_segqlen--; 328 q = nq; 329 } while (q && q->tqe_th->th_seq == tp->rcv_nxt); 330 sorwakeup_locked(so); 331 return (flags); 332 } 333