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 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_maxqlen) = 48;
  96 #define V_tcp_reass_maxqlen             VNET(tcp_reass_maxqlen)
  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 static VNET_DEFINE(int, tcp_reass_overflows) = 0;
 102 #define V_tcp_reass_overflows           VNET(tcp_reass_overflows)
 103 SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD,
 104     &VNET_NAME(tcp_reass_overflows), 0,
 105     "Global number of TCP Segment Reassembly Queue Overflows");
 106
 107 static VNET_DEFINE(uma_zone_t, tcp_reass_zone);
 108 #define V_tcp_reass_zone                VNET(tcp_reass_zone)
 109
 110 /* Initialize TCP reassembly queue */
 111 static void
 112 tcp_reass_zone_change(void *tag)
 113 {
 114
 115         V_tcp_reass_maxseg = nmbclusters / 16;
 116         uma_zone_set_max(V_tcp_reass_zone, V_tcp_reass_maxseg);
 117 }
 118
 119 void
 120 tcp_reass_init(void)
 121 {
 122
 123         V_tcp_reass_maxseg = nmbclusters / 16;
 124         TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments",
 125             &V_tcp_reass_maxseg);
 126         V_tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent),
 127             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
 128         uma_zone_set_max(V_tcp_reass_zone, V_tcp_reass_maxseg);
 129         EVENTHANDLER_REGISTER(nmbclusters_change,
 130             tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY);
 131 }
 132
 133 #ifdef VIMAGE
 134 void
 135 tcp_reass_destroy(void)
 136 {
 137
 138         uma_zdestroy(V_tcp_reass_zone);
 139 }
 140 #endif
 141
 142 void
 143 tcp_reass_flush(struct tcpcb *tp)
 144 {
 145         struct tseg_qent *qe;
 146
 147         INP_WLOCK_ASSERT(tp->t_inpcb);
 148
 149         while ((qe = LIST_FIRST(&tp->t_segq)) != NULL) {
 150                 LIST_REMOVE(qe, tqe_q);
 151                 m_freem(qe->tqe_m);
 152                 uma_zfree(V_tcp_reass_zone, qe);
 153                 tp->t_segqlen--;
 154         }
 155
 156         KASSERT((tp->t_segqlen == 0),
 157             ("TCP reass queue %p segment count is %d instead of 0 after flush.",
 158             tp, tp->t_segqlen));
 159 }
 160
 161 static int
 162 tcp_reass_sysctl_maxseg(SYSCTL_HANDLER_ARGS)
 163 {
 164         V_tcp_reass_maxseg = uma_zone_get_max(V_tcp_reass_zone);
 165         return (sysctl_handle_int(oidp, arg1, arg2, req));
 166 }
 167
 168 static int
 169 tcp_reass_sysctl_qsize(SYSCTL_HANDLER_ARGS)
 170 {
 171         V_tcp_reass_qsize = uma_zone_get_cur(V_tcp_reass_zone);
 172         return (sysctl_handle_int(oidp, arg1, arg2, req));
 173 }
 174
 175 int
 176 tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m)
 177 {
 178         struct tseg_qent *q;
 179         struct tseg_qent *p = NULL;
 180         struct tseg_qent *nq;
 181         struct tseg_qent *te = NULL;
 182         struct socket *so = tp->t_inpcb->inp_socket;
 183         int flags;
 184
 185         INP_WLOCK_ASSERT(tp->t_inpcb);
 186
 187         /*
 188          * XXX: tcp_reass() is rather inefficient with its data structures
 189          * and should be rewritten (see NetBSD for optimizations).
 190          */
 191
 192         /*
 193          * Call with th==NULL after become established to
 194          * force pre-ESTABLISHED data up to user socket.
 195          */
 196         if (th == NULL)
 197                 goto present;
 198
 199         /*
 200          * Limit the number of segments in the reassembly queue to prevent
 201          * holding on to too many segments (and thus running out of mbufs).
 202          * Make sure to let the missing segment through which caused this
 203          * queue.
 204          */
 205         if (th->th_seq != tp->rcv_nxt &&
 206             tp->t_segqlen >= V_tcp_reass_maxqlen) {
 207                 V_tcp_reass_overflows++;
 208                 TCPSTAT_INC(tcps_rcvmemdrop);
 209                 m_freem(m);
 210                 *tlenp = 0;
 211                 return (0);
 212         }
 213
 214         /*
 215          * Allocate a new queue entry. If we can't, or hit the zone limit
 216          * just drop the pkt.
 217          */
 218         te = uma_zalloc(V_tcp_reass_zone, M_NOWAIT);
 219         if (te == NULL) {
 220                 TCPSTAT_INC(tcps_rcvmemdrop);
 221                 m_freem(m);
 222                 *tlenp = 0;
 223                 return (0);
 224         }
 225         tp->t_segqlen++;
 226
 227         /*
 228          * Find a segment which begins after this one does.
 229          */
 230         LIST_FOREACH(q, &tp->t_segq, tqe_q) {
 231                 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq))
 232                         break;
 233                 p = q;
 234         }
 235
 236         /*
 237          * If there is a preceding segment, it may provide some of
 238          * our data already.  If so, drop the data from the incoming
 239          * segment.  If it provides all of our data, drop us.
 240          */
 241         if (p != NULL) {
 242                 int i;
 243                 /* conversion to int (in i) handles seq wraparound */
 244                 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq;
 245                 if (i > 0) {
 246                         if (i >= *tlenp) {
 247                                 TCPSTAT_INC(tcps_rcvduppack);
 248                                 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
 249                                 m_freem(m);
 250                                 uma_zfree(V_tcp_reass_zone, te);
 251                                 tp->t_segqlen--;
 252                                 /*
 253                                  * Try to present any queued data
 254                                  * at the left window edge to the user.
 255                                  * This is needed after the 3-WHS
 256                                  * completes.
 257                                  */
 258                                 goto present;   /* ??? */
 259                         }
 260                         m_adj(m, i);
 261                         *tlenp -= i;
 262                         th->th_seq += i;
 263                 }
 264         }
 265         TCPSTAT_INC(tcps_rcvoopack);
 266         TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
 267
 268         /*
 269          * While we overlap succeeding segments trim them or,
 270          * if they are completely covered, dequeue them.
 271          */
 272         while (q) {
 273                 int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq;
 274                 if (i <= 0)
 275                         break;
 276                 if (i < q->tqe_len) {
 277                         q->tqe_th->th_seq += i;
 278                         q->tqe_len -= i;
 279                         m_adj(q->tqe_m, i);
 280                         break;
 281                 }
 282
 283                 nq = LIST_NEXT(q, tqe_q);
 284                 LIST_REMOVE(q, tqe_q);
 285                 m_freem(q->tqe_m);
 286                 uma_zfree(V_tcp_reass_zone, q);
 287                 tp->t_segqlen--;
 288                 q = nq;
 289         }
 290
 291         /* Insert the new segment queue entry into place. */
 292         te->tqe_m = m;
 293         te->tqe_th = th;
 294         te->tqe_len = *tlenp;
 295
 296         if (p == NULL) {
 297                 LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q);
 298         } else {
 299                 LIST_INSERT_AFTER(p, te, tqe_q);
 300         }
 301
 302 present:
 303         /*
 304          * Present data to user, advancing rcv_nxt through
 305          * completed sequence space.
 306          */
 307         if (!TCPS_HAVEESTABLISHED(tp->t_state))
 308                 return (0);
 309         q = LIST_FIRST(&tp->t_segq);
 310         if (!q || q->tqe_th->th_seq != tp->rcv_nxt)
 311                 return (0);
 312         SOCKBUF_LOCK(&so->so_rcv);
 313         do {
 314                 tp->rcv_nxt += q->tqe_len;
 315                 flags = q->tqe_th->th_flags & TH_FIN;
 316                 nq = LIST_NEXT(q, tqe_q);
 317                 LIST_REMOVE(q, tqe_q);
 318                 if (so->so_rcv.sb_state & SBS_CANTRCVMORE)
 319                         m_freem(q->tqe_m);
 320                 else
 321                         sbappendstream_locked(&so->so_rcv, q->tqe_m);
 322                 uma_zfree(V_tcp_reass_zone, q);
 323                 tp->t_segqlen--;
 324                 q = nq;
 325         } while (q && q->tqe_th->th_seq == tp->rcv_nxt);
 326         ND6_HINT(tp);
 327         sorwakeup_locked(so);
 328         return (flags);
 329 }