The Design and Implementation of the FreeBSD Operating System, Second Edition
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sys/netinet6/in6_rmx.c

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    1 /*-
    2  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
    3  * 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  * 3. Neither the name of the project 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 PROJECT 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 PROJECT 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  *      $KAME: in6_rmx.c,v 1.11 2001/07/26 06:53:16 jinmei Exp $
   30  */
   31 
   32 /*-
   33  * Copyright 1994, 1995 Massachusetts Institute of Technology
   34  *
   35  * Permission to use, copy, modify, and distribute this software and
   36  * its documentation for any purpose and without fee is hereby
   37  * granted, provided that both the above copyright notice and this
   38  * permission notice appear in all copies, that both the above
   39  * copyright notice and this permission notice appear in all
   40  * supporting documentation, and that the name of M.I.T. not be used
   41  * in advertising or publicity pertaining to distribution of the
   42  * software without specific, written prior permission.  M.I.T. makes
   43  * no representations about the suitability of this software for any
   44  * purpose.  It is provided "as is" without express or implied
   45  * warranty.
   46  *
   47  * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''.  M.I.T. DISCLAIMS
   48  * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
   49  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   50  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
   51  * SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   52  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   53  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   54  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   55  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   56  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   57  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   58  * SUCH DAMAGE.
   59  *
   60  */
   61 
   62 /*
   63  * This code does two things necessary for the enhanced TCP metrics to
   64  * function in a useful manner:
   65  *  1) It marks all non-host routes as `cloning', thus ensuring that
   66  *     every actual reference to such a route actually gets turned
   67  *     into a reference to a host route to the specific destination
   68  *     requested.
   69  *  2) When such routes lose all their references, it arranges for them
   70  *     to be deleted in some random collection of circumstances, so that
   71  *     a large quantity of stale routing data is not kept in kernel memory
   72  *     indefinitely.  See in6_rtqtimo() below for the exact mechanism.
   73  */
   74 
   75 #include <sys/cdefs.h>
   76 __FBSDID("$FreeBSD: releng/9.0/sys/netinet6/in6_rmx.c 215701 2010-11-22 19:32:54Z dim $");
   77 
   78 #include <sys/param.h>
   79 #include <sys/systm.h>
   80 #include <sys/kernel.h>
   81 #include <sys/lock.h>
   82 #include <sys/sysctl.h>
   83 #include <sys/queue.h>
   84 #include <sys/socket.h>
   85 #include <sys/socketvar.h>
   86 #include <sys/mbuf.h>
   87 #include <sys/rwlock.h>
   88 #include <sys/syslog.h>
   89 #include <sys/callout.h>
   90 
   91 #include <net/if.h>
   92 #include <net/route.h>
   93 
   94 #include <netinet/in.h>
   95 #include <netinet/ip_var.h>
   96 #include <netinet/in_var.h>
   97 
   98 #include <netinet/ip6.h>
   99 #include <netinet6/ip6_var.h>
  100 
  101 #include <netinet/icmp6.h>
  102 #include <netinet6/nd6.h>
  103 
  104 #include <netinet/tcp.h>
  105 #include <netinet/tcp_seq.h>
  106 #include <netinet/tcp_timer.h>
  107 #include <netinet/tcp_var.h>
  108 
  109 extern int      in6_inithead(void **head, int off);
  110 #ifdef VIMAGE
  111 extern int      in6_detachhead(void **head, int off);
  112 #endif
  113 
  114 #define RTPRF_OURS              RTF_PROTO3      /* set on routes we manage */
  115 
  116 /*
  117  * Do what we need to do when inserting a route.
  118  */
  119 static struct radix_node *
  120 in6_addroute(void *v_arg, void *n_arg, struct radix_node_head *head,
  121     struct radix_node *treenodes)
  122 {
  123         struct rtentry *rt = (struct rtentry *)treenodes;
  124         struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)rt_key(rt);
  125         struct radix_node *ret;
  126 
  127         RADIX_NODE_HEAD_WLOCK_ASSERT(head);
  128         if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
  129                 rt->rt_flags |= RTF_MULTICAST;
  130 
  131         /*
  132          * A little bit of help for both IPv6 output and input:
  133          *   For local addresses, we make sure that RTF_LOCAL is set,
  134          *   with the thought that this might one day be used to speed up
  135          *   ip_input().
  136          *
  137          * We also mark routes to multicast addresses as such, because
  138          * it's easy to do and might be useful (but this is much more
  139          * dubious since it's so easy to inspect the address).  (This
  140          * is done above.)
  141          *
  142          * XXX
  143          * should elaborate the code.
  144          */
  145         if (rt->rt_flags & RTF_HOST) {
  146                 if (IN6_ARE_ADDR_EQUAL(&satosin6(rt->rt_ifa->ifa_addr)
  147                                         ->sin6_addr,
  148                                        &sin6->sin6_addr)) {
  149                         rt->rt_flags |= RTF_LOCAL;
  150                 }
  151         }
  152 
  153         if (!rt->rt_rmx.rmx_mtu && rt->rt_ifp)
  154                 rt->rt_rmx.rmx_mtu = IN6_LINKMTU(rt->rt_ifp);
  155 
  156         ret = rn_addroute(v_arg, n_arg, head, treenodes);
  157         if (ret == NULL) {
  158                 struct rtentry *rt2;
  159                 /*
  160                  * We are trying to add a net route, but can't.
  161                  * The following case should be allowed, so we'll make a
  162                  * special check for this:
  163                  *      Two IPv6 addresses with the same prefix is assigned
  164                  *      to a single interrface.
  165                  *      # ifconfig if0 inet6 3ffe:0501::1 prefix 64 alias (*1)
  166                  *      # ifconfig if0 inet6 3ffe:0501::2 prefix 64 alias (*2)
  167                  *      In this case, (*1) and (*2) want to add the same
  168                  *      net route entry, 3ffe:0501:: -> if0.
  169                  *      This case should not raise an error.
  170                  */
  171                 rt2 = rtalloc1((struct sockaddr *)sin6, 0, RTF_RNH_LOCKED);
  172                 if (rt2) {
  173                         if (((rt2->rt_flags & (RTF_HOST|RTF_GATEWAY)) == 0)
  174                          && rt2->rt_gateway
  175                          && rt2->rt_gateway->sa_family == AF_LINK
  176                          && rt2->rt_ifp == rt->rt_ifp) {
  177                                 ret = rt2->rt_nodes;
  178                         }
  179                         RTFREE_LOCKED(rt2);
  180                 }
  181         }
  182         return (ret);
  183 }
  184 
  185 /*
  186  * This code is the inverse of in6_clsroute: on first reference, if we
  187  * were managing the route, stop doing so and set the expiration timer
  188  * back off again.
  189  */
  190 static struct radix_node *
  191 in6_matroute(void *v_arg, struct radix_node_head *head)
  192 {
  193         struct radix_node *rn = rn_match(v_arg, head);
  194         struct rtentry *rt = (struct rtentry *)rn;
  195 
  196         if (rt) {
  197                 RT_LOCK(rt);
  198                 if (rt->rt_flags & RTPRF_OURS) {
  199                         rt->rt_flags &= ~RTPRF_OURS;
  200                         rt->rt_rmx.rmx_expire = 0;
  201                 }
  202                 RT_UNLOCK(rt);
  203         }
  204         return rn;
  205 }
  206 
  207 SYSCTL_DECL(_net_inet6_ip6);
  208 
  209 static VNET_DEFINE(int, rtq_reallyold6) = 60*60;
  210         /* one hour is ``really old'' */
  211 #define V_rtq_reallyold6                VNET(rtq_reallyold6)
  212 SYSCTL_VNET_INT(_net_inet6_ip6, IPV6CTL_RTEXPIRE, rtexpire, CTLFLAG_RW,
  213     &VNET_NAME(rtq_reallyold6) , 0, "");
  214 
  215 static VNET_DEFINE(int, rtq_minreallyold6) = 10;
  216         /* never automatically crank down to less */
  217 #define V_rtq_minreallyold6             VNET(rtq_minreallyold6)
  218 SYSCTL_VNET_INT(_net_inet6_ip6, IPV6CTL_RTMINEXPIRE, rtminexpire, CTLFLAG_RW,
  219     &VNET_NAME(rtq_minreallyold6) , 0, "");
  220 
  221 static VNET_DEFINE(int, rtq_toomany6) = 128;
  222         /* 128 cached routes is ``too many'' */
  223 #define V_rtq_toomany6                  VNET(rtq_toomany6)
  224 SYSCTL_VNET_INT(_net_inet6_ip6, IPV6CTL_RTMAXCACHE, rtmaxcache, CTLFLAG_RW,
  225     &VNET_NAME(rtq_toomany6) , 0, "");
  226 
  227 struct rtqk_arg {
  228         struct radix_node_head *rnh;
  229         int mode;
  230         int updating;
  231         int draining;
  232         int killed;
  233         int found;
  234         time_t nextstop;
  235 };
  236 
  237 /*
  238  * Get rid of old routes.  When draining, this deletes everything, even when
  239  * the timeout is not expired yet.  When updating, this makes sure that
  240  * nothing has a timeout longer than the current value of rtq_reallyold6.
  241  */
  242 static int
  243 in6_rtqkill(struct radix_node *rn, void *rock)
  244 {
  245         struct rtqk_arg *ap = rock;
  246         struct rtentry *rt = (struct rtentry *)rn;
  247         int err;
  248 
  249         RADIX_NODE_HEAD_WLOCK_ASSERT(ap->rnh);
  250 
  251         if (rt->rt_flags & RTPRF_OURS) {
  252                 ap->found++;
  253 
  254                 if (ap->draining || rt->rt_rmx.rmx_expire <= time_uptime) {
  255                         if (rt->rt_refcnt > 0)
  256                                 panic("rtqkill route really not free");
  257 
  258                         err = rtrequest(RTM_DELETE,
  259                                         (struct sockaddr *)rt_key(rt),
  260                                         rt->rt_gateway, rt_mask(rt),
  261                                         rt->rt_flags|RTF_RNH_LOCKED, 0);
  262                         if (err) {
  263                                 log(LOG_WARNING, "in6_rtqkill: error %d", err);
  264                         } else {
  265                                 ap->killed++;
  266                         }
  267                 } else {
  268                         if (ap->updating
  269                            && (rt->rt_rmx.rmx_expire - time_uptime
  270                                > V_rtq_reallyold6)) {
  271                                 rt->rt_rmx.rmx_expire = time_uptime
  272                                         + V_rtq_reallyold6;
  273                         }
  274                         ap->nextstop = lmin(ap->nextstop,
  275                                             rt->rt_rmx.rmx_expire);
  276                 }
  277         }
  278 
  279         return 0;
  280 }
  281 
  282 #define RTQ_TIMEOUT     60*10   /* run no less than once every ten minutes */
  283 static VNET_DEFINE(int, rtq_timeout6) = RTQ_TIMEOUT;
  284 static VNET_DEFINE(struct callout, rtq_timer6);
  285 
  286 #define V_rtq_timeout6                  VNET(rtq_timeout6)
  287 #define V_rtq_timer6                    VNET(rtq_timer6)
  288 
  289 static void
  290 in6_rtqtimo(void *rock)
  291 {
  292         CURVNET_SET_QUIET((struct vnet *) rock);
  293         struct radix_node_head *rnh;
  294         struct rtqk_arg arg;
  295         struct timeval atv;
  296         static time_t last_adjusted_timeout = 0;
  297 
  298         rnh = rt_tables_get_rnh(0, AF_INET6);
  299         if (rnh == NULL) {
  300                 CURVNET_RESTORE();
  301                 return;
  302         }
  303         arg.found = arg.killed = 0;
  304         arg.rnh = rnh;
  305         arg.nextstop = time_uptime + V_rtq_timeout6;
  306         arg.draining = arg.updating = 0;
  307         RADIX_NODE_HEAD_LOCK(rnh);
  308         rnh->rnh_walktree(rnh, in6_rtqkill, &arg);
  309         RADIX_NODE_HEAD_UNLOCK(rnh);
  310 
  311         /*
  312          * Attempt to be somewhat dynamic about this:
  313          * If there are ``too many'' routes sitting around taking up space,
  314          * then crank down the timeout, and see if we can't make some more
  315          * go away.  However, we make sure that we will never adjust more
  316          * than once in rtq_timeout6 seconds, to keep from cranking down too
  317          * hard.
  318          */
  319         if ((arg.found - arg.killed > V_rtq_toomany6)
  320            && (time_uptime - last_adjusted_timeout >= V_rtq_timeout6)
  321            && V_rtq_reallyold6 > V_rtq_minreallyold6) {
  322                 V_rtq_reallyold6 = 2*V_rtq_reallyold6 / 3;
  323                 if (V_rtq_reallyold6 < V_rtq_minreallyold6) {
  324                         V_rtq_reallyold6 = V_rtq_minreallyold6;
  325                 }
  326 
  327                 last_adjusted_timeout = time_uptime;
  328 #ifdef DIAGNOSTIC
  329                 log(LOG_DEBUG, "in6_rtqtimo: adjusted rtq_reallyold6 to %d",
  330                     V_rtq_reallyold6);
  331 #endif
  332                 arg.found = arg.killed = 0;
  333                 arg.updating = 1;
  334                 RADIX_NODE_HEAD_LOCK(rnh);
  335                 rnh->rnh_walktree(rnh, in6_rtqkill, &arg);
  336                 RADIX_NODE_HEAD_UNLOCK(rnh);
  337         }
  338 
  339         atv.tv_usec = 0;
  340         atv.tv_sec = arg.nextstop - time_uptime;
  341         callout_reset(&V_rtq_timer6, tvtohz(&atv), in6_rtqtimo, rock);
  342         CURVNET_RESTORE();
  343 }
  344 
  345 /*
  346  * Age old PMTUs.
  347  */
  348 struct mtuex_arg {
  349         struct radix_node_head *rnh;
  350         time_t nextstop;
  351 };
  352 static VNET_DEFINE(struct callout, rtq_mtutimer);
  353 #define V_rtq_mtutimer                  VNET(rtq_mtutimer)
  354 
  355 static int
  356 in6_mtuexpire(struct radix_node *rn, void *rock)
  357 {
  358         struct rtentry *rt = (struct rtentry *)rn;
  359         struct mtuex_arg *ap = rock;
  360 
  361         /* sanity */
  362         if (!rt)
  363                 panic("rt == NULL in in6_mtuexpire");
  364 
  365         if (rt->rt_rmx.rmx_expire && !(rt->rt_flags & RTF_PROBEMTU)) {
  366                 if (rt->rt_rmx.rmx_expire <= time_uptime) {
  367                         rt->rt_flags |= RTF_PROBEMTU;
  368                 } else {
  369                         ap->nextstop = lmin(ap->nextstop,
  370                                         rt->rt_rmx.rmx_expire);
  371                 }
  372         }
  373 
  374         return 0;
  375 }
  376 
  377 #define MTUTIMO_DEFAULT (60*1)
  378 
  379 static void
  380 in6_mtutimo(void *rock)
  381 {
  382         CURVNET_SET_QUIET((struct vnet *) rock);
  383         struct radix_node_head *rnh;
  384         struct mtuex_arg arg;
  385         struct timeval atv;
  386 
  387         rnh = rt_tables_get_rnh(0, AF_INET6);
  388         if (rnh == NULL) {
  389                 CURVNET_RESTORE();
  390                 return;
  391         }
  392         arg.rnh = rnh;
  393         arg.nextstop = time_uptime + MTUTIMO_DEFAULT;
  394         RADIX_NODE_HEAD_LOCK(rnh);
  395         rnh->rnh_walktree(rnh, in6_mtuexpire, &arg);
  396         RADIX_NODE_HEAD_UNLOCK(rnh);
  397 
  398         atv.tv_usec = 0;
  399         atv.tv_sec = arg.nextstop - time_uptime;
  400         if (atv.tv_sec < 0) {
  401                 printf("invalid mtu expiration time on routing table\n");
  402                 arg.nextstop = time_uptime + 30;        /* last resort */
  403                 atv.tv_sec = 30;
  404         }
  405         callout_reset(&V_rtq_mtutimer, tvtohz(&atv), in6_mtutimo, rock);
  406         CURVNET_RESTORE();
  407 }
  408 
  409 /*
  410  * Initialize our routing tree.
  411  * XXX MRT When off == 0, we are being called from vfs_export.c
  412  * so just set up their table and leave. (we know what the correct
  413  * value should be so just use that).. FIX AFTER RELENG_7 is MFC'd
  414  * see also comments in in_inithead() vfs_export.c and domain.h
  415  */
  416 int
  417 in6_inithead(void **head, int off)
  418 {
  419         struct radix_node_head *rnh;
  420 
  421         if (!rn_inithead(head, offsetof(struct sockaddr_in6, sin6_addr) << 3))
  422                 return 0;               /* See above */
  423 
  424         if (off == 0)           /* See above */
  425                 return 1;       /* only do the rest for the real thing */
  426 
  427         rnh = *head;
  428         KASSERT(rnh == rt_tables_get_rnh(0, AF_INET6), ("rnh?"));
  429         rnh->rnh_addaddr = in6_addroute;
  430         rnh->rnh_matchaddr = in6_matroute;
  431         callout_init(&V_rtq_timer6, CALLOUT_MPSAFE);
  432         callout_init(&V_rtq_mtutimer, CALLOUT_MPSAFE);
  433         in6_rtqtimo(curvnet);   /* kick off timeout first time */
  434         in6_mtutimo(curvnet);   /* kick off timeout first time */
  435         return 1;
  436 }
  437 
  438 #ifdef VIMAGE
  439 int
  440 in6_detachhead(void **head, int off)
  441 {
  442 
  443         callout_drain(&V_rtq_timer6);
  444         callout_drain(&V_rtq_mtutimer);
  445         return (1);
  446 }
  447 #endif

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