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 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0, 78 "TCP Segment Reassembly Queue"); 79 80 static VNET_DEFINE(int, tcp_reass_maxseg) = 0; 81 #define V_tcp_reass_maxseg VNET(tcp_reass_maxseg) 82 SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN, 83 &VNET_NAME(tcp_reass_maxseg), 0, 84 "Global maximum number of TCP Segments in Reassembly Queue"); 85 86 VNET_DEFINE(int, tcp_reass_qsize) = 0; 87 SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, cursegments, CTLFLAG_RD, 88 &VNET_NAME(tcp_reass_qsize), 0, 89 "Global number of TCP Segments currently in Reassembly Queue"); 90 91 static VNET_DEFINE(int, tcp_reass_maxqlen) = 48; 92 #define V_tcp_reass_maxqlen VNET(tcp_reass_maxqlen) 93 SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, maxqlen, CTLFLAG_RW, 94 &VNET_NAME(tcp_reass_maxqlen), 0, 95 "Maximum number of TCP Segments per individual Reassembly Queue"); 96 97 static VNET_DEFINE(int, tcp_reass_overflows) = 0; 98 #define V_tcp_reass_overflows VNET(tcp_reass_overflows) 99 SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD, 100 &VNET_NAME(tcp_reass_overflows), 0, 101 "Global number of TCP Segment Reassembly Queue Overflows"); 102 103 /* Initialize TCP reassembly queue */ 104 static void 105 tcp_reass_zone_change(void *tag) 106 { 107 108 V_tcp_reass_maxseg = nmbclusters / 16; 109 uma_zone_set_max(V_tcp_reass_zone, V_tcp_reass_maxseg); 110 } 111 112 VNET_DEFINE(uma_zone_t, tcp_reass_zone); 113 114 void 115 tcp_reass_init(void) 116 { 117 118 V_tcp_reass_maxseg = nmbclusters / 16; 119 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", 120 &V_tcp_reass_maxseg); 121 V_tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent), 122 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 123 uma_zone_set_max(V_tcp_reass_zone, V_tcp_reass_maxseg); 124 EVENTHANDLER_REGISTER(nmbclusters_change, 125 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY); 126 } 127 128 #ifdef VIMAGE 129 void 130 tcp_reass_destroy(void) 131 { 132 133 uma_zdestroy(V_tcp_reass_zone); 134 } 135 #endif 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 int flags; 146 147 INP_WLOCK_ASSERT(tp->t_inpcb); 148 149 /* 150 * XXX: tcp_reass() is rather inefficient with its data structures 151 * and should be rewritten (see NetBSD for optimizations). 152 */ 153 154 /* 155 * Call with th==NULL after become established to 156 * force pre-ESTABLISHED data up to user socket. 157 */ 158 if (th == NULL) 159 goto present; 160 161 /* 162 * Limit the number of segments in the reassembly queue to prevent 163 * holding on to too many segments (and thus running out of mbufs). 164 * Make sure to let the missing segment through which caused this 165 * queue. Always keep one global queue entry spare to be able to 166 * process the missing segment. 167 */ 168 if (th->th_seq != tp->rcv_nxt && 169 (V_tcp_reass_qsize + 1 >= V_tcp_reass_maxseg || 170 tp->t_segqlen >= V_tcp_reass_maxqlen)) { 171 V_tcp_reass_overflows++; 172 TCPSTAT_INC(tcps_rcvmemdrop); 173 m_freem(m); 174 *tlenp = 0; 175 return (0); 176 } 177 178 /* 179 * Allocate a new queue entry. If we can't, or hit the zone limit 180 * just drop the pkt. 181 */ 182 te = uma_zalloc(V_tcp_reass_zone, M_NOWAIT); 183 if (te == NULL) { 184 TCPSTAT_INC(tcps_rcvmemdrop); 185 m_freem(m); 186 *tlenp = 0; 187 return (0); 188 } 189 tp->t_segqlen++; 190 V_tcp_reass_qsize++; 191 192 /* 193 * Find a segment which begins after this one does. 194 */ 195 LIST_FOREACH(q, &tp->t_segq, tqe_q) { 196 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq)) 197 break; 198 p = q; 199 } 200 201 /* 202 * If there is a preceding segment, it may provide some of 203 * our data already. If so, drop the data from the incoming 204 * segment. If it provides all of our data, drop us. 205 */ 206 if (p != NULL) { 207 int i; 208 /* conversion to int (in i) handles seq wraparound */ 209 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq; 210 if (i > 0) { 211 if (i >= *tlenp) { 212 TCPSTAT_INC(tcps_rcvduppack); 213 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 214 m_freem(m); 215 uma_zfree(V_tcp_reass_zone, te); 216 tp->t_segqlen--; 217 V_tcp_reass_qsize--; 218 /* 219 * Try to present any queued data 220 * at the left window edge to the user. 221 * This is needed after the 3-WHS 222 * completes. 223 */ 224 goto present; /* ??? */ 225 } 226 m_adj(m, i); 227 *tlenp -= i; 228 th->th_seq += i; 229 } 230 } 231 TCPSTAT_INC(tcps_rcvoopack); 232 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); 233 234 /* 235 * While we overlap succeeding segments trim them or, 236 * if they are completely covered, dequeue them. 237 */ 238 while (q) { 239 int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq; 240 if (i <= 0) 241 break; 242 if (i < q->tqe_len) { 243 q->tqe_th->th_seq += i; 244 q->tqe_len -= i; 245 m_adj(q->tqe_m, i); 246 break; 247 } 248 249 nq = LIST_NEXT(q, tqe_q); 250 LIST_REMOVE(q, tqe_q); 251 m_freem(q->tqe_m); 252 uma_zfree(V_tcp_reass_zone, q); 253 tp->t_segqlen--; 254 V_tcp_reass_qsize--; 255 q = nq; 256 } 257 258 /* Insert the new segment queue entry into place. */ 259 te->tqe_m = m; 260 te->tqe_th = th; 261 te->tqe_len = *tlenp; 262 263 if (p == NULL) { 264 LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q); 265 } else { 266 LIST_INSERT_AFTER(p, te, tqe_q); 267 } 268 269 present: 270 /* 271 * Present data to user, advancing rcv_nxt through 272 * completed sequence space. 273 */ 274 if (!TCPS_HAVEESTABLISHED(tp->t_state)) 275 return (0); 276 q = LIST_FIRST(&tp->t_segq); 277 if (!q || q->tqe_th->th_seq != tp->rcv_nxt) 278 return (0); 279 SOCKBUF_LOCK(&so->so_rcv); 280 do { 281 tp->rcv_nxt += q->tqe_len; 282 flags = q->tqe_th->th_flags & TH_FIN; 283 nq = LIST_NEXT(q, tqe_q); 284 LIST_REMOVE(q, tqe_q); 285 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 286 m_freem(q->tqe_m); 287 else 288 sbappendstream_locked(&so->so_rcv, q->tqe_m); 289 uma_zfree(V_tcp_reass_zone, q); 290 tp->t_segqlen--; 291 V_tcp_reass_qsize--; 292 q = nq; 293 } while (q && q->tqe_th->th_seq == tp->rcv_nxt); 294 ND6_HINT(tp); 295 sorwakeup_locked(so); 296 return (flags); 297 } 298