sys/netinet/tcp_reass.c

   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 #ifdef VIMAGE
 136 void
 137 tcp_reass_destroy(void)
 138 {
 139
 140         uma_zdestroy(V_tcp_reass_zone);
 141 }
 142 #endif
 143
 144 int
 145 tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m)
 146 {
 147         struct tseg_qent *q;
 148         struct tseg_qent *p = NULL;
 149         struct tseg_qent *nq;
 150         struct tseg_qent *te = NULL;
 151         struct socket *so = tp->t_inpcb->inp_socket;
 152         int flags;
 153
 154         INP_WLOCK_ASSERT(tp->t_inpcb);
 155
 156         /*
 157          * XXX: tcp_reass() is rather inefficient with its data structures
 158          * and should be rewritten (see NetBSD for optimizations).
 159          */
 160
 161         /*
 162          * Call with th==NULL after become established to
 163          * force pre-ESTABLISHED data up to user socket.
 164          */
 165         if (th == NULL)
 166                 goto present;
 167
 168         /*
 169          * Limit the number of segments in the reassembly queue to prevent
 170          * holding on to too many segments (and thus running out of mbufs).
 171          * Make sure to let the missing segment through which caused this
 172          * queue.  Always keep one global queue entry spare to be able to
 173          * process the missing segment.
 174          */
 175         if (th->th_seq != tp->rcv_nxt &&
 176             (V_tcp_reass_qsize + 1 >= V_tcp_reass_maxseg ||
 177              tp->t_segqlen >= V_tcp_reass_maxqlen)) {
 178                 V_tcp_reass_overflows++;
 179                 TCPSTAT_INC(tcps_rcvmemdrop);
 180                 m_freem(m);
 181                 *tlenp = 0;
 182                 return (0);
 183         }
 184
 185         /*
 186          * Allocate a new queue entry. If we can't, or hit the zone limit
 187          * just drop the pkt.
 188          */
 189         te = uma_zalloc(V_tcp_reass_zone, M_NOWAIT);
 190         if (te == NULL) {
 191                 TCPSTAT_INC(tcps_rcvmemdrop);
 192                 m_freem(m);
 193                 *tlenp = 0;
 194                 return (0);
 195         }
 196         tp->t_segqlen++;
 197         V_tcp_reass_qsize++;
 198
 199         /*
 200          * Find a segment which begins after this one does.
 201          */
 202         LIST_FOREACH(q, &tp->t_segq, tqe_q) {
 203                 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq))
 204                         break;
 205                 p = q;
 206         }
 207
 208         /*
 209          * If there is a preceding segment, it may provide some of
 210          * our data already.  If so, drop the data from the incoming
 211          * segment.  If it provides all of our data, drop us.
 212          */
 213         if (p != NULL) {
 214                 int i;
 215                 /* conversion to int (in i) handles seq wraparound */
 216                 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq;
 217                 if (i > 0) {
 218                         if (i >= *tlenp) {
 219                                 TCPSTAT_INC(tcps_rcvduppack);
 220                                 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
 221                                 m_freem(m);
 222                                 uma_zfree(V_tcp_reass_zone, te);
 223                                 tp->t_segqlen--;
 224                                 V_tcp_reass_qsize--;
 225                                 /*
 226                                  * Try to present any queued data
 227                                  * at the left window edge to the user.
 228                                  * This is needed after the 3-WHS
 229                                  * completes.
 230                                  */
 231                                 goto present;   /* ??? */
 232                         }
 233                         m_adj(m, i);
 234                         *tlenp -= i;
 235                         th->th_seq += i;
 236                 }
 237         }
 238         TCPSTAT_INC(tcps_rcvoopack);
 239         TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
 240
 241         /*
 242          * While we overlap succeeding segments trim them or,
 243          * if they are completely covered, dequeue them.
 244          */
 245         while (q) {
 246                 int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq;
 247                 if (i <= 0)
 248                         break;
 249                 if (i < q->tqe_len) {
 250                         q->tqe_th->th_seq += i;
 251                         q->tqe_len -= i;
 252                         m_adj(q->tqe_m, i);
 253                         break;
 254                 }
 255
 256                 nq = LIST_NEXT(q, tqe_q);
 257                 LIST_REMOVE(q, tqe_q);
 258                 m_freem(q->tqe_m);
 259                 uma_zfree(V_tcp_reass_zone, q);
 260                 tp->t_segqlen--;
 261                 V_tcp_reass_qsize--;
 262                 q = nq;
 263         }
 264
 265         /* Insert the new segment queue entry into place. */
 266         te->tqe_m = m;
 267         te->tqe_th = th;
 268         te->tqe_len = *tlenp;
 269
 270         if (p == NULL) {
 271                 LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q);
 272         } else {
 273                 LIST_INSERT_AFTER(p, te, tqe_q);
 274         }
 275
 276 present:
 277         /*
 278          * Present data to user, advancing rcv_nxt through
 279          * completed sequence space.
 280          */
 281         if (!TCPS_HAVEESTABLISHED(tp->t_state))
 282                 return (0);
 283         q = LIST_FIRST(&tp->t_segq);
 284         if (!q || q->tqe_th->th_seq != tp->rcv_nxt)
 285                 return (0);
 286         SOCKBUF_LOCK(&so->so_rcv);
 287         do {
 288                 tp->rcv_nxt += q->tqe_len;
 289                 flags = q->tqe_th->th_flags & TH_FIN;
 290                 nq = LIST_NEXT(q, tqe_q);
 291                 LIST_REMOVE(q, tqe_q);
 292                 if (so->so_rcv.sb_state & SBS_CANTRCVMORE)
 293                         m_freem(q->tqe_m);
 294                 else
 295                         sbappendstream_locked(&so->so_rcv, q->tqe_m);
 296                 uma_zfree(V_tcp_reass_zone, q);
 297                 tp->t_segqlen--;
 298                 V_tcp_reass_qsize--;
 299                 q = nq;
 300         } while (q && q->tqe_th->th_seq == tp->rcv_nxt);
 301         ND6_HINT(tp);
 302         sorwakeup_locked(so);
 303         return (flags);
 304 }