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_maxseg(SYSCTL_HANDLER_ARGS); 78 static int tcp_reass_sysctl_qsize(SYSCTL_HANDLER_ARGS); 79 80 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0, 81 "TCP Segment Reassembly Queue"); 82 83 static VNET_DEFINE(int, tcp_reass_maxseg) = 0; 84 #define V_tcp_reass_maxseg VNET(tcp_reass_maxseg) 85 SYSCTL_VNET_PROC(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN, 86 &VNET_NAME(tcp_reass_maxseg), 0, &tcp_reass_sysctl_maxseg, "I", 87 "Global maximum number of TCP Segments in Reassembly Queue"); 88 89 static VNET_DEFINE(int, tcp_reass_qsize) = 0; 90 #define V_tcp_reass_qsize VNET(tcp_reass_qsize) 91 SYSCTL_VNET_PROC(_net_inet_tcp_reass, OID_AUTO, cursegments, CTLFLAG_RD, 92 &VNET_NAME(tcp_reass_qsize), 0, &tcp_reass_sysctl_qsize, "I", 93 "Global number of TCP Segments currently in Reassembly Queue"); 94 95 static VNET_DEFINE(int, tcp_reass_overflows) = 0; 96 #define V_tcp_reass_overflows VNET(tcp_reass_overflows) 97 SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD, 98 &VNET_NAME(tcp_reass_overflows), 0, 99 "Global number of TCP Segment Reassembly Queue Overflows"); 100 101 static VNET_DEFINE(uma_zone_t, tcp_reass_zone); 102 #define V_tcp_reass_zone VNET(tcp_reass_zone) 103 104 /* Initialize TCP reassembly queue */ 105 static void 106 tcp_reass_zone_change(void *tag) 107 { 108 109 V_tcp_reass_maxseg = nmbclusters / 16; 110 uma_zone_set_max(V_tcp_reass_zone, V_tcp_reass_maxseg); 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 uma_zone_set_max(V_tcp_reass_zone, 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 static int 156 tcp_reass_sysctl_maxseg(SYSCTL_HANDLER_ARGS) 157 { 158 V_tcp_reass_maxseg = uma_zone_get_max(V_tcp_reass_zone); 159 return (sysctl_handle_int(oidp, arg1, arg2, req)); 160 } 161 162 static int 163 tcp_reass_sysctl_qsize(SYSCTL_HANDLER_ARGS) 164 { 165 V_tcp_reass_qsize = uma_zone_get_cur(V_tcp_reass_zone); 166 return (sysctl_handle_int(oidp, arg1, arg2, req)); 167 } 168 169 int 170 tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m) 171 { 172 struct tseg_qent *q; 173 struct tseg_qent *p = NULL; 174 struct tseg_qent *nq; 175 struct tseg_qent *te = NULL; 176 struct socket *so = tp->t_inpcb->inp_socket; 177 int flags; 178 179 INP_WLOCK_ASSERT(tp->t_inpcb); 180 181 /* 182 * XXX: tcp_reass() is rather inefficient with its data structures 183 * and should be rewritten (see NetBSD for optimizations). 184 */ 185 186 /* 187 * Call with th==NULL after become established to 188 * force pre-ESTABLISHED data up to user socket. 189 */ 190 if (th == NULL) 191 goto present; 192 193 /* 194 * Limit the number of segments that can be queued to reduce the 195 * potential for mbuf exhaustion. For best performance, we want to be 196 * able to queue a full window's worth of segments. The size of the 197 * socket receive buffer determines our advertised window and grows 198 * automatically when socket buffer autotuning is enabled. Use it as the 199 * basis for our queue limit. 200 * Always let the missing segment through which caused this queue. 201 * NB: Access to the socket buffer is left intentionally unlocked as we 202 * can tolerate stale information here. 203 * 204 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat 205 * should work but causes packets to be dropped when they shouldn't. 206 * Investigate why and re-evaluate the below limit after the behaviour 207 * is understood. 208 */ 209 if (th->th_seq != tp->rcv_nxt && 210 tp->t_segqlen >= (so->so_rcv.sb_hiwat / tp->t_maxseg) + 1) { 211 V_tcp_reass_overflows++; 212 TCPSTAT_INC(tcps_rcvmemdrop); 213 m_freem(m); 214 *tlenp = 0; 215 return (0); 216 } 217 218 /* 219 * Allocate a new queue entry. If we can't, or hit the zone limit 220 * just drop the pkt. 221 */ 222 te = uma_zalloc(V_tcp_reass_zone, M_NOWAIT); 223 if (te == NULL) { 224 TCPSTAT_INC(tcps_rcvmemdrop); 225 m_freem(m); 226 *tlenp = 0; 227 return (0); 228 } 229 tp->t_segqlen++; 230 231 /* 232 * Find a segment which begins after this one does. 233 */ 234 LIST_FOREACH(q, &tp->t_segq, tqe_q) { 235 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq)) 236 break; 237 p = q; 238 } 239 240 /* 241 * If there is a preceding segment, it may provide some of 242 * our data already. If so, drop the data from the incoming 243 * segment. If it provides all of our data, drop us. 244 */ 245 if (p != NULL) { 246 int i; 247 /* conversion to int (in i) handles seq wraparound */ 248 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq; 249 if (i > 0) { 250 if (i >= *tlenp) { 251 TCPSTAT_INC(tcps_rcvduppack); 252 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 253 m_freem(m); 254 uma_zfree(V_tcp_reass_zone, te); 255 tp->t_segqlen--; 256 /* 257 * Try to present any queued data 258 * at the left window edge to the user. 259 * This is needed after the 3-WHS 260 * completes. 261 */ 262 goto present; /* ??? */ 263 } 264 m_adj(m, i); 265 *tlenp -= i; 266 th->th_seq += i; 267 } 268 } 269 TCPSTAT_INC(tcps_rcvoopack); 270 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); 271 272 /* 273 * While we overlap succeeding segments trim them or, 274 * if they are completely covered, dequeue them. 275 */ 276 while (q) { 277 int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq; 278 if (i <= 0) 279 break; 280 if (i < q->tqe_len) { 281 q->tqe_th->th_seq += i; 282 q->tqe_len -= i; 283 m_adj(q->tqe_m, i); 284 break; 285 } 286 287 nq = LIST_NEXT(q, tqe_q); 288 LIST_REMOVE(q, tqe_q); 289 m_freem(q->tqe_m); 290 uma_zfree(V_tcp_reass_zone, q); 291 tp->t_segqlen--; 292 q = nq; 293 } 294 295 /* Insert the new segment queue entry into place. */ 296 te->tqe_m = m; 297 te->tqe_th = th; 298 te->tqe_len = *tlenp; 299 300 if (p == NULL) { 301 LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q); 302 } else { 303 LIST_INSERT_AFTER(p, te, tqe_q); 304 } 305 306 present: 307 /* 308 * Present data to user, advancing rcv_nxt through 309 * completed sequence space. 310 */ 311 if (!TCPS_HAVEESTABLISHED(tp->t_state)) 312 return (0); 313 q = LIST_FIRST(&tp->t_segq); 314 if (!q || q->tqe_th->th_seq != tp->rcv_nxt) 315 return (0); 316 SOCKBUF_LOCK(&so->so_rcv); 317 do { 318 tp->rcv_nxt += q->tqe_len; 319 flags = q->tqe_th->th_flags & TH_FIN; 320 nq = LIST_NEXT(q, tqe_q); 321 LIST_REMOVE(q, tqe_q); 322 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 323 m_freem(q->tqe_m); 324 else 325 sbappendstream_locked(&so->so_rcv, q->tqe_m); 326 uma_zfree(V_tcp_reass_zone, q); 327 tp->t_segqlen--; 328 q = nq; 329 } while (q && q->tqe_th->th_seq == tp->rcv_nxt); 330 ND6_HINT(tp); 331 sorwakeup_locked(so); 332 return (flags); 333 } 334