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 VNET_DEFINE(int, tcp_reass_maxseg); 78 VNET_DEFINE(int, tcp_reass_qsize); 79 static VNET_DEFINE(int, tcp_reass_maxqlen); 80 static VNET_DEFINE(int, tcp_reass_overflows); 81 82 #define V_tcp_reass_maxseg VNET(tcp_reass_maxseg) 83 #define V_tcp_reass_maxqlen VNET(tcp_reass_maxqlen) 84 #define V_tcp_reass_overflows VNET(tcp_reass_overflows) 85 86 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0, 87 "TCP Segment Reassembly Queue"); 88 89 SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN, 90 &VNET_NAME(tcp_reass_maxseg), 0, 91 "Global maximum number of TCP Segments in Reassembly Queue"); 92 93 SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, cursegments, CTLFLAG_RD, 94 &VNET_NAME(tcp_reass_qsize), 0, 95 "Global number of TCP Segments currently in Reassembly Queue"); 96 97 SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, maxqlen, CTLFLAG_RW, 98 &VNET_NAME(tcp_reass_maxqlen), 0, 99 "Maximum number of TCP Segments per individual Reassembly Queue"); 100 101 SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD, 102 &VNET_NAME(tcp_reass_overflows), 0, 103 "Global number of TCP Segment Reassembly Queue Overflows"); 104 105 /* Initialize TCP reassembly queue */ 106 static void 107 tcp_reass_zone_change(void *tag) 108 { 109 110 V_tcp_reass_maxseg = nmbclusters / 16; 111 uma_zone_set_max(V_tcp_reass_zone, V_tcp_reass_maxseg); 112 } 113 114 VNET_DEFINE(uma_zone_t, tcp_reass_zone); 115 116 void 117 tcp_reass_init(void) 118 { 119 120 V_tcp_reass_maxseg = 0; 121 V_tcp_reass_qsize = 0; 122 V_tcp_reass_maxqlen = 48; 123 V_tcp_reass_overflows = 0; 124 125 V_tcp_reass_maxseg = nmbclusters / 16; 126 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", 127 &V_tcp_reass_maxseg); 128 V_tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent), 129 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 130 uma_zone_set_max(V_tcp_reass_zone, V_tcp_reass_maxseg); 131 EVENTHANDLER_REGISTER(nmbclusters_change, 132 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY); 133 } 134 135 int 136 tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m) 137 { 138 struct tseg_qent *q; 139 struct tseg_qent *p = NULL; 140 struct tseg_qent *nq; 141 struct tseg_qent *te = NULL; 142 struct socket *so = tp->t_inpcb->inp_socket; 143 int flags; 144 145 INP_WLOCK_ASSERT(tp->t_inpcb); 146 147 /* 148 * XXX: tcp_reass() is rather inefficient with its data structures 149 * and should be rewritten (see NetBSD for optimizations). 150 */ 151 152 /* 153 * Call with th==NULL after become established to 154 * force pre-ESTABLISHED data up to user socket. 155 */ 156 if (th == NULL) 157 goto present; 158 159 /* 160 * Limit the number of segments in the reassembly queue to prevent 161 * holding on to too many segments (and thus running out of mbufs). 162 * Make sure to let the missing segment through which caused this 163 * queue. Always keep one global queue entry spare to be able to 164 * process the missing segment. 165 */ 166 if (th->th_seq != tp->rcv_nxt && 167 (V_tcp_reass_qsize + 1 >= V_tcp_reass_maxseg || 168 tp->t_segqlen >= V_tcp_reass_maxqlen)) { 169 V_tcp_reass_overflows++; 170 TCPSTAT_INC(tcps_rcvmemdrop); 171 m_freem(m); 172 *tlenp = 0; 173 return (0); 174 } 175 176 /* 177 * Allocate a new queue entry. If we can't, or hit the zone limit 178 * just drop the pkt. 179 */ 180 te = uma_zalloc(V_tcp_reass_zone, M_NOWAIT); 181 if (te == NULL) { 182 TCPSTAT_INC(tcps_rcvmemdrop); 183 m_freem(m); 184 *tlenp = 0; 185 return (0); 186 } 187 tp->t_segqlen++; 188 V_tcp_reass_qsize++; 189 190 /* 191 * Find a segment which begins after this one does. 192 */ 193 LIST_FOREACH(q, &tp->t_segq, tqe_q) { 194 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq)) 195 break; 196 p = q; 197 } 198 199 /* 200 * If there is a preceding segment, it may provide some of 201 * our data already. If so, drop the data from the incoming 202 * segment. If it provides all of our data, drop us. 203 */ 204 if (p != NULL) { 205 int i; 206 /* conversion to int (in i) handles seq wraparound */ 207 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq; 208 if (i > 0) { 209 if (i >= *tlenp) { 210 TCPSTAT_INC(tcps_rcvduppack); 211 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 212 m_freem(m); 213 uma_zfree(V_tcp_reass_zone, te); 214 tp->t_segqlen--; 215 V_tcp_reass_qsize--; 216 /* 217 * Try to present any queued data 218 * at the left window edge to the user. 219 * This is needed after the 3-WHS 220 * completes. 221 */ 222 goto present; /* ??? */ 223 } 224 m_adj(m, i); 225 *tlenp -= i; 226 th->th_seq += i; 227 } 228 } 229 TCPSTAT_INC(tcps_rcvoopack); 230 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); 231 232 /* 233 * While we overlap succeeding segments trim them or, 234 * if they are completely covered, dequeue them. 235 */ 236 while (q) { 237 int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq; 238 if (i <= 0) 239 break; 240 if (i < q->tqe_len) { 241 q->tqe_th->th_seq += i; 242 q->tqe_len -= i; 243 m_adj(q->tqe_m, i); 244 break; 245 } 246 247 nq = LIST_NEXT(q, tqe_q); 248 LIST_REMOVE(q, tqe_q); 249 m_freem(q->tqe_m); 250 uma_zfree(V_tcp_reass_zone, q); 251 tp->t_segqlen--; 252 V_tcp_reass_qsize--; 253 q = nq; 254 } 255 256 /* Insert the new segment queue entry into place. */ 257 te->tqe_m = m; 258 te->tqe_th = th; 259 te->tqe_len = *tlenp; 260 261 if (p == NULL) { 262 LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q); 263 } else { 264 LIST_INSERT_AFTER(p, te, tqe_q); 265 } 266 267 present: 268 /* 269 * Present data to user, advancing rcv_nxt through 270 * completed sequence space. 271 */ 272 if (!TCPS_HAVEESTABLISHED(tp->t_state)) 273 return (0); 274 q = LIST_FIRST(&tp->t_segq); 275 if (!q || q->tqe_th->th_seq != tp->rcv_nxt) 276 return (0); 277 SOCKBUF_LOCK(&so->so_rcv); 278 do { 279 tp->rcv_nxt += q->tqe_len; 280 flags = q->tqe_th->th_flags & TH_FIN; 281 nq = LIST_NEXT(q, tqe_q); 282 LIST_REMOVE(q, tqe_q); 283 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 284 m_freem(q->tqe_m); 285 else 286 sbappendstream_locked(&so->so_rcv, q->tqe_m); 287 uma_zfree(V_tcp_reass_zone, q); 288 tp->t_segqlen--; 289 V_tcp_reass_qsize--; 290 q = nq; 291 } while (q && q->tqe_th->th_seq == tp->rcv_nxt); 292 ND6_HINT(tp); 293 sorwakeup_locked(so); 294 return (flags); 295 } 296