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 VNET_DEFINE(int, tcp_reass_maxseg) = 0; 82 #define V_tcp_reass_maxseg VNET(tcp_reass_maxseg) 83 SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN, 84 &VNET_NAME(tcp_reass_maxseg), 0, 85 "Global maximum number of TCP Segments in Reassembly Queue"); 86 87 static VNET_DEFINE(int, tcp_reass_overflows) = 0; 88 #define V_tcp_reass_overflows VNET(tcp_reass_overflows) 89 SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, overflows, 90 CTLTYPE_INT | CTLFLAG_RD, 91 &VNET_NAME(tcp_reass_overflows), 0, 92 "Global number of TCP Segment Reassembly Queue Overflows"); 93 94 static VNET_DEFINE(uma_zone_t, tcp_reass_zone); 95 #define V_tcp_reass_zone VNET(tcp_reass_zone) 96 SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, CTLFLAG_VNET, 97 &VNET_NAME(tcp_reass_zone), 98 "Global number of TCP Segments currently in Reassembly Queue"); 99 100 /* Initialize TCP reassembly queue */ 101 static void 102 tcp_reass_zone_change(void *tag) 103 { 104 105 /* Set the zone limit and read back the effective value. */ 106 V_tcp_reass_maxseg = nmbclusters / 16; 107 V_tcp_reass_maxseg = uma_zone_set_max(V_tcp_reass_zone, 108 V_tcp_reass_maxseg); 109 } 110 111 void 112 tcp_reass_init(void) 113 { 114 115 V_tcp_reass_maxseg = nmbclusters / 16; 116 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", 117 &V_tcp_reass_maxseg); 118 V_tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent), 119 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 120 /* Set the zone limit and read back the effective value. */ 121 V_tcp_reass_maxseg = uma_zone_set_max(V_tcp_reass_zone, 122 V_tcp_reass_maxseg); 123 EVENTHANDLER_REGISTER(nmbclusters_change, 124 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY); 125 } 126 127 #ifdef VIMAGE 128 void 129 tcp_reass_destroy(void) 130 { 131 132 uma_zdestroy(V_tcp_reass_zone); 133 } 134 #endif 135 136 void 137 tcp_reass_flush(struct tcpcb *tp) 138 { 139 struct tseg_qent *qe; 140 141 INP_WLOCK_ASSERT(tp->t_inpcb); 142 143 while ((qe = LIST_FIRST(&tp->t_segq)) != NULL) { 144 LIST_REMOVE(qe, tqe_q); 145 m_freem(qe->tqe_m); 146 uma_zfree(V_tcp_reass_zone, qe); 147 tp->t_segqlen--; 148 } 149 150 KASSERT((tp->t_segqlen == 0), 151 ("TCP reass queue %p segment count is %d instead of 0 after flush.", 152 tp, tp->t_segqlen)); 153 } 154 155 int 156 tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m) 157 { 158 struct tseg_qent *q; 159 struct tseg_qent *p = NULL; 160 struct tseg_qent *nq; 161 struct tseg_qent *te = NULL; 162 struct socket *so = tp->t_inpcb->inp_socket; 163 char *s = NULL; 164 int flags; 165 struct tseg_qent tqs; 166 167 INP_WLOCK_ASSERT(tp->t_inpcb); 168 169 /* 170 * XXX: tcp_reass() is rather inefficient with its data structures 171 * and should be rewritten (see NetBSD for optimizations). 172 */ 173 174 /* 175 * Call with th==NULL after become established to 176 * force pre-ESTABLISHED data up to user socket. 177 */ 178 if (th == NULL) 179 goto present; 180 181 /* 182 * Limit the number of segments that can be queued to reduce the 183 * potential for mbuf exhaustion. For best performance, we want to be 184 * able to queue a full window's worth of segments. The size of the 185 * socket receive buffer determines our advertised window and grows 186 * automatically when socket buffer autotuning is enabled. Use it as the 187 * basis for our queue limit. 188 * Always let the missing segment through which caused this queue. 189 * NB: Access to the socket buffer is left intentionally unlocked as we 190 * can tolerate stale information here. 191 * 192 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat 193 * should work but causes packets to be dropped when they shouldn't. 194 * Investigate why and re-evaluate the below limit after the behaviour 195 * is understood. 196 */ 197 if (th->th_seq != tp->rcv_nxt && 198 tp->t_segqlen >= (so->so_rcv.sb_hiwat / tp->t_maxseg) + 1) { 199 V_tcp_reass_overflows++; 200 TCPSTAT_INC(tcps_rcvmemdrop); 201 m_freem(m); 202 *tlenp = 0; 203 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { 204 log(LOG_DEBUG, "%s; %s: queue limit reached, " 205 "segment dropped\n", s, __func__); 206 free(s, M_TCPLOG); 207 } 208 return (0); 209 } 210 211 /* 212 * Allocate a new queue entry. If we can't, or hit the zone limit 213 * just drop the pkt. 214 * 215 * Use a temporary structure on the stack for the missing segment 216 * when the zone is exhausted. Otherwise we may get stuck. 217 */ 218 te = uma_zalloc(V_tcp_reass_zone, M_NOWAIT); 219 if (te == NULL) { 220 if (th->th_seq != tp->rcv_nxt) { 221 TCPSTAT_INC(tcps_rcvmemdrop); 222 m_freem(m); 223 *tlenp = 0; 224 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, 225 NULL))) { 226 log(LOG_DEBUG, "%s; %s: global zone limit " 227 "reached, segment dropped\n", s, __func__); 228 free(s, M_TCPLOG); 229 } 230 return (0); 231 } else { 232 bzero(&tqs, sizeof(struct tseg_qent)); 233 te = &tqs; 234 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, 235 NULL))) { 236 log(LOG_DEBUG, 237 "%s; %s: global zone limit reached, using " 238 "stack for missing segment\n", s, __func__); 239 free(s, M_TCPLOG); 240 } 241 } 242 } 243 tp->t_segqlen++; 244 245 /* 246 * Find a segment which begins after this one does. 247 */ 248 LIST_FOREACH(q, &tp->t_segq, tqe_q) { 249 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq)) 250 break; 251 p = q; 252 } 253 254 /* 255 * If there is a preceding segment, it may provide some of 256 * our data already. If so, drop the data from the incoming 257 * segment. If it provides all of our data, drop us. 258 */ 259 if (p != NULL) { 260 int i; 261 /* conversion to int (in i) handles seq wraparound */ 262 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq; 263 if (i > 0) { 264 if (i >= *tlenp) { 265 TCPSTAT_INC(tcps_rcvduppack); 266 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 267 m_freem(m); 268 uma_zfree(V_tcp_reass_zone, te); 269 tp->t_segqlen--; 270 /* 271 * Try to present any queued data 272 * at the left window edge to the user. 273 * This is needed after the 3-WHS 274 * completes. 275 */ 276 goto present; /* ??? */ 277 } 278 m_adj(m, i); 279 *tlenp -= i; 280 th->th_seq += i; 281 } 282 } 283 tp->t_rcvoopack++; 284 TCPSTAT_INC(tcps_rcvoopack); 285 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); 286 287 /* 288 * While we overlap succeeding segments trim them or, 289 * if they are completely covered, dequeue them. 290 */ 291 while (q) { 292 int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq; 293 if (i <= 0) 294 break; 295 if (i < q->tqe_len) { 296 q->tqe_th->th_seq += i; 297 q->tqe_len -= i; 298 m_adj(q->tqe_m, i); 299 break; 300 } 301 302 nq = LIST_NEXT(q, tqe_q); 303 LIST_REMOVE(q, tqe_q); 304 m_freem(q->tqe_m); 305 uma_zfree(V_tcp_reass_zone, q); 306 tp->t_segqlen--; 307 q = nq; 308 } 309 310 /* Insert the new segment queue entry into place. */ 311 te->tqe_m = m; 312 te->tqe_th = th; 313 te->tqe_len = *tlenp; 314 315 if (p == NULL) { 316 LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q); 317 } else { 318 KASSERT(te != &tqs, ("%s: temporary stack based entry not " 319 "first element in queue", __func__)); 320 LIST_INSERT_AFTER(p, te, tqe_q); 321 } 322 323 present: 324 /* 325 * Present data to user, advancing rcv_nxt through 326 * completed sequence space. 327 */ 328 if (!TCPS_HAVEESTABLISHED(tp->t_state)) 329 return (0); 330 q = LIST_FIRST(&tp->t_segq); 331 if (!q || q->tqe_th->th_seq != tp->rcv_nxt) 332 return (0); 333 SOCKBUF_LOCK(&so->so_rcv); 334 do { 335 tp->rcv_nxt += q->tqe_len; 336 flags = q->tqe_th->th_flags & TH_FIN; 337 nq = LIST_NEXT(q, tqe_q); 338 LIST_REMOVE(q, tqe_q); 339 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 340 m_freem(q->tqe_m); 341 else 342 sbappendstream_locked(&so->so_rcv, q->tqe_m); 343 if (q != &tqs) 344 uma_zfree(V_tcp_reass_zone, q); 345 tp->t_segqlen--; 346 q = nq; 347 } while (q && q->tqe_th->th_seq == tp->rcv_nxt); 348 ND6_HINT(tp); 349 sorwakeup_locked(so); 350 return (flags); 351 } 352