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/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 77 static int tcp_reass_sysctl_qsize(SYSCTL_HANDLER_ARGS); 78 79 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0, 80 "TCP Segment Reassembly Queue"); 81 82 static VNET_DEFINE(int, tcp_reass_maxseg) = 0; 83 #define V_tcp_reass_maxseg VNET(tcp_reass_maxseg) 84 SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN, 85 &VNET_NAME(tcp_reass_maxseg), 0, 86 "Global maximum number of TCP Segments in Reassembly Queue"); 87 88 SYSCTL_VNET_PROC(_net_inet_tcp_reass, OID_AUTO, cursegments, 89 (CTLTYPE_INT | CTLFLAG_RD), NULL, 0, &tcp_reass_sysctl_qsize, "I", 90 "Global number of TCP Segments currently in Reassembly Queue"); 91 92 static VNET_DEFINE(int, tcp_reass_overflows) = 0; 93 #define V_tcp_reass_overflows VNET(tcp_reass_overflows) 94 SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, overflows, 95 CTLTYPE_INT | CTLFLAG_RD, 96 &VNET_NAME(tcp_reass_overflows), 0, 97 "Global number of TCP Segment Reassembly Queue Overflows"); 98 99 static VNET_DEFINE(uma_zone_t, tcp_reass_zone); 100 #define V_tcp_reass_zone VNET(tcp_reass_zone) 101 102 /* Initialize TCP reassembly queue */ 103 static void 104 tcp_reass_zone_change(void *tag) 105 { 106 107 /* Set the zone limit and read back the effective value. */ 108 V_tcp_reass_maxseg = nmbclusters / 16; 109 uma_zone_set_max(V_tcp_reass_zone, V_tcp_reass_maxseg); 110 V_tcp_reass_maxseg = uma_zone_get_max(V_tcp_reass_zone); 111 } 112 113 void 114 tcp_reass_init(void) 115 { 116 117 V_tcp_reass_maxseg = nmbclusters / 16; 118 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", 119 &V_tcp_reass_maxseg); 120 V_tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent), 121 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 122 /* Set the zone limit and read back the effective value. */ 123 uma_zone_set_max(V_tcp_reass_zone, V_tcp_reass_maxseg); 124 V_tcp_reass_maxseg = uma_zone_get_max(V_tcp_reass_zone); 125 EVENTHANDLER_REGISTER(nmbclusters_change, 126 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY); 127 } 128 129 #ifdef VIMAGE 130 void 131 tcp_reass_destroy(void) 132 { 133 134 uma_zdestroy(V_tcp_reass_zone); 135 } 136 #endif 137 138 void 139 tcp_reass_flush(struct tcpcb *tp) 140 { 141 struct tseg_qent *qe; 142 143 INP_WLOCK_ASSERT(tp->t_inpcb); 144 145 while ((qe = LIST_FIRST(&tp->t_segq)) != NULL) { 146 LIST_REMOVE(qe, tqe_q); 147 m_freem(qe->tqe_m); 148 uma_zfree(V_tcp_reass_zone, qe); 149 tp->t_segqlen--; 150 } 151 152 KASSERT((tp->t_segqlen == 0), 153 ("TCP reass queue %p segment count is %d instead of 0 after flush.", 154 tp, tp->t_segqlen)); 155 } 156 157 static int 158 tcp_reass_sysctl_qsize(SYSCTL_HANDLER_ARGS) 159 { 160 int qsize; 161 162 qsize = uma_zone_get_cur(V_tcp_reass_zone); 163 return (sysctl_handle_int(oidp, &qsize, sizeof(qsize), req)); 164 } 165 166 int 167 tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m) 168 { 169 struct tseg_qent *q; 170 struct tseg_qent *p = NULL; 171 struct tseg_qent *nq; 172 struct tseg_qent *te = NULL; 173 struct socket *so = tp->t_inpcb->inp_socket; 174 char *s = NULL; 175 int flags; 176 struct tseg_qent tqs; 177 178 INP_WLOCK_ASSERT(tp->t_inpcb); 179 180 /* 181 * XXX: tcp_reass() is rather inefficient with its data structures 182 * and should be rewritten (see NetBSD for optimizations). 183 */ 184 185 /* 186 * Call with th==NULL after become established to 187 * force pre-ESTABLISHED data up to user socket. 188 */ 189 if (th == NULL) 190 goto present; 191 192 /* 193 * Limit the number of segments that can be queued to reduce the 194 * potential for mbuf exhaustion. For best performance, we want to be 195 * able to queue a full window's worth of segments. The size of the 196 * socket receive buffer determines our advertised window and grows 197 * automatically when socket buffer autotuning is enabled. Use it as the 198 * basis for our queue limit. 199 * Always let the missing segment through which caused this queue. 200 * NB: Access to the socket buffer is left intentionally unlocked as we 201 * can tolerate stale information here. 202 * 203 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat 204 * should work but causes packets to be dropped when they shouldn't. 205 * Investigate why and re-evaluate the below limit after the behaviour 206 * is understood. 207 */ 208 if (th->th_seq != tp->rcv_nxt && 209 tp->t_segqlen >= (so->so_rcv.sb_hiwat / tp->t_maxseg) + 1) { 210 V_tcp_reass_overflows++; 211 TCPSTAT_INC(tcps_rcvmemdrop); 212 m_freem(m); 213 *tlenp = 0; 214 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { 215 log(LOG_DEBUG, "%s; %s: queue limit reached, " 216 "segment dropped\n", s, __func__); 217 free(s, M_TCPLOG); 218 } 219 return (0); 220 } 221 222 /* 223 * Allocate a new queue entry. If we can't, or hit the zone limit 224 * just drop the pkt. 225 * 226 * Use a temporary structure on the stack for the missing segment 227 * when the zone is exhausted. Otherwise we may get stuck. 228 */ 229 te = uma_zalloc(V_tcp_reass_zone, M_NOWAIT); 230 if (te == NULL) { 231 if (th->th_seq != tp->rcv_nxt) { 232 TCPSTAT_INC(tcps_rcvmemdrop); 233 m_freem(m); 234 *tlenp = 0; 235 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, 236 NULL))) { 237 log(LOG_DEBUG, "%s; %s: global zone limit " 238 "reached, segment dropped\n", s, __func__); 239 free(s, M_TCPLOG); 240 } 241 return (0); 242 } else { 243 bzero(&tqs, sizeof(struct tseg_qent)); 244 te = &tqs; 245 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, 246 NULL))) { 247 log(LOG_DEBUG, 248 "%s; %s: global zone limit reached, using " 249 "stack for missing segment\n", s, __func__); 250 free(s, M_TCPLOG); 251 } 252 } 253 } 254 tp->t_segqlen++; 255 256 /* 257 * Find a segment which begins after this one does. 258 */ 259 LIST_FOREACH(q, &tp->t_segq, tqe_q) { 260 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq)) 261 break; 262 p = q; 263 } 264 265 /* 266 * If there is a preceding segment, it may provide some of 267 * our data already. If so, drop the data from the incoming 268 * segment. If it provides all of our data, drop us. 269 */ 270 if (p != NULL) { 271 int i; 272 /* conversion to int (in i) handles seq wraparound */ 273 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq; 274 if (i > 0) { 275 if (i >= *tlenp) { 276 TCPSTAT_INC(tcps_rcvduppack); 277 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 278 m_freem(m); 279 uma_zfree(V_tcp_reass_zone, te); 280 tp->t_segqlen--; 281 /* 282 * Try to present any queued data 283 * at the left window edge to the user. 284 * This is needed after the 3-WHS 285 * completes. 286 */ 287 goto present; /* ??? */ 288 } 289 m_adj(m, i); 290 *tlenp -= i; 291 th->th_seq += i; 292 } 293 } 294 tp->t_rcvoopack++; 295 TCPSTAT_INC(tcps_rcvoopack); 296 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); 297 298 /* 299 * While we overlap succeeding segments trim them or, 300 * if they are completely covered, dequeue them. 301 */ 302 while (q) { 303 int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq; 304 if (i <= 0) 305 break; 306 if (i < q->tqe_len) { 307 q->tqe_th->th_seq += i; 308 q->tqe_len -= i; 309 m_adj(q->tqe_m, i); 310 break; 311 } 312 313 nq = LIST_NEXT(q, tqe_q); 314 LIST_REMOVE(q, tqe_q); 315 m_freem(q->tqe_m); 316 uma_zfree(V_tcp_reass_zone, q); 317 tp->t_segqlen--; 318 q = nq; 319 } 320 321 /* Insert the new segment queue entry into place. */ 322 te->tqe_m = m; 323 te->tqe_th = th; 324 te->tqe_len = *tlenp; 325 326 if (p == NULL) { 327 LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q); 328 } else { 329 KASSERT(te != &tqs, ("%s: temporary stack based entry not " 330 "first element in queue", __func__)); 331 LIST_INSERT_AFTER(p, te, tqe_q); 332 } 333 334 present: 335 /* 336 * Present data to user, advancing rcv_nxt through 337 * completed sequence space. 338 */ 339 if (!TCPS_HAVEESTABLISHED(tp->t_state)) 340 return (0); 341 q = LIST_FIRST(&tp->t_segq); 342 if (!q || q->tqe_th->th_seq != tp->rcv_nxt) 343 return (0); 344 SOCKBUF_LOCK(&so->so_rcv); 345 do { 346 tp->rcv_nxt += q->tqe_len; 347 flags = q->tqe_th->th_flags & TH_FIN; 348 nq = LIST_NEXT(q, tqe_q); 349 LIST_REMOVE(q, tqe_q); 350 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 351 m_freem(q->tqe_m); 352 else 353 sbappendstream_locked(&so->so_rcv, q->tqe_m); 354 if (q != &tqs) 355 uma_zfree(V_tcp_reass_zone, q); 356 tp->t_segqlen--; 357 q = nq; 358 } while (q && q->tqe_th->th_seq == tp->rcv_nxt); 359 ND6_HINT(tp); 360 sorwakeup_locked(so); 361 return (flags); 362 } 363