The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
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("$FreeBSD$");
   77 
   78 #include <sys/param.h>
   79 #include <sys/systm.h>
   80 #include <sys/kernel.h>
   81 #include <sys/sysctl.h>
   82 #include <sys/queue.h>
   83 #include <sys/socket.h>
   84 #include <sys/socketvar.h>
   85 #include <sys/mbuf.h>
   86 #include <sys/syslog.h>
   87 #include <sys/callout.h>
   88 
   89 #include <net/if.h>
   90 #include <net/route.h>
   91 #include <netinet/in.h>
   92 #include <netinet/ip_var.h>
   93 #include <netinet/in_var.h>
   94 
   95 #include <netinet/ip6.h>
   96 #include <netinet6/ip6_var.h>
   97 
   98 #include <netinet/icmp6.h>
   99 #include <netinet6/nd6.h>
  100 
  101 #include <netinet/tcp.h>
  102 #include <netinet/tcp_seq.h>
  103 #include <netinet/tcp_timer.h>
  104 #include <netinet/tcp_var.h>
  105 
  106 extern int      in6_inithead(void **head, int off);
  107 
  108 #define RTPRF_OURS              RTF_PROTO3      /* set on routes we manage */
  109 
  110 /*
  111  * Do what we need to do when inserting a route.
  112  */
  113 static struct radix_node *
  114 in6_addroute(void *v_arg, void *n_arg, struct radix_node_head *head,
  115     struct radix_node *treenodes)
  116 {
  117         struct rtentry *rt = (struct rtentry *)treenodes;
  118         struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)rt_key(rt);
  119         struct radix_node *ret;
  120 
  121         if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
  122                 rt->rt_flags |= RTF_MULTICAST;
  123 
  124         /*
  125          * A little bit of help for both IPv6 output and input:
  126          *   For local addresses, we make sure that RTF_LOCAL is set,
  127          *   with the thought that this might one day be used to speed up
  128          *   ip_input().
  129          *
  130          * We also mark routes to multicast addresses as such, because
  131          * it's easy to do and might be useful (but this is much more
  132          * dubious since it's so easy to inspect the address).  (This
  133          * is done above.)
  134          *
  135          * XXX
  136          * should elaborate the code.
  137          */
  138         if (rt->rt_flags & RTF_HOST) {
  139                 if (IN6_ARE_ADDR_EQUAL(&satosin6(rt->rt_ifa->ifa_addr)
  140                                         ->sin6_addr,
  141                                        &sin6->sin6_addr)) {
  142                         rt->rt_flags |= RTF_LOCAL;
  143                 }
  144         }
  145 
  146         if (!rt->rt_rmx.rmx_mtu && rt->rt_ifp)
  147                 rt->rt_rmx.rmx_mtu = IN6_LINKMTU(rt->rt_ifp);
  148 
  149         ret = rn_addroute(v_arg, n_arg, head, treenodes);
  150         if (ret == NULL && rt->rt_flags & RTF_HOST) {
  151                 struct rtentry *rt2;
  152                 /*
  153                  * We are trying to add a host route, but can't.
  154                  * Find out if it is because of an
  155                  * ARP entry and delete it if so.
  156                  */
  157                 rt2 = rtalloc1((struct sockaddr *)sin6, 0, RTF_RNH_LOCKED|RTF_CLONING);
  158                 if (rt2) {
  159                         if (rt2->rt_flags & RTF_LLINFO &&
  160                                 rt2->rt_flags & RTF_HOST &&
  161                                 rt2->rt_gateway &&
  162                                 rt2->rt_gateway->sa_family == AF_LINK) {
  163                                 rtexpunge(rt2);
  164                                 RTFREE_LOCKED(rt2);
  165                                 ret = rn_addroute(v_arg, n_arg, head,
  166                                         treenodes);
  167                         } else
  168                                 RTFREE_LOCKED(rt2);
  169                 }
  170         } else if (ret == NULL && rt->rt_flags & RTF_CLONING) {
  171                 struct rtentry *rt2;
  172                 /*
  173                  * We are trying to add a net route, but can't.
  174                  * The following case should be allowed, so we'll make a
  175                  * special check for this:
  176                  *      Two IPv6 addresses with the same prefix is assigned
  177                  *      to a single interrface.
  178                  *      # ifconfig if0 inet6 3ffe:0501::1 prefix 64 alias (*1)
  179                  *      # ifconfig if0 inet6 3ffe:0501::2 prefix 64 alias (*2)
  180                  *      In this case, (*1) and (*2) want to add the same
  181                  *      net route entry, 3ffe:0501:: -> if0.
  182                  *      This case should not raise an error.
  183                  */
  184                 rt2 = rtalloc1((struct sockaddr *)sin6, 0, RTF_RNH_LOCKED|RTF_CLONING);
  185                 if (rt2) {
  186                         if ((rt2->rt_flags & (RTF_CLONING|RTF_HOST|RTF_GATEWAY))
  187                                         == RTF_CLONING
  188                          && rt2->rt_gateway
  189                          && rt2->rt_gateway->sa_family == AF_LINK
  190                          && rt2->rt_ifp == rt->rt_ifp) {
  191                                 ret = rt2->rt_nodes;
  192                         }
  193                         RTFREE_LOCKED(rt2);
  194                 }
  195         }
  196         return ret;
  197 }
  198 
  199 /*
  200  * This code is the inverse of in6_clsroute: on first reference, if we
  201  * were managing the route, stop doing so and set the expiration timer
  202  * back off again.
  203  */
  204 static struct radix_node *
  205 in6_matroute(void *v_arg, struct radix_node_head *head)
  206 {
  207         struct radix_node *rn = rn_match(v_arg, head);
  208         struct rtentry *rt = (struct rtentry *)rn;
  209 
  210         if (rt && rt->rt_refcnt == 0) { /* this is first reference */
  211                 if (rt->rt_flags & RTPRF_OURS) {
  212                         rt->rt_flags &= ~RTPRF_OURS;
  213                         rt->rt_rmx.rmx_expire = 0;
  214                 }
  215         }
  216         return rn;
  217 }
  218 
  219 SYSCTL_DECL(_net_inet6_ip6);
  220 
  221 static int rtq_reallyold = 60*60;
  222         /* one hour is ``really old'' */
  223 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_RTEXPIRE, rtexpire,
  224         CTLFLAG_RW, &rtq_reallyold , 0, "");
  225 
  226 static int rtq_minreallyold = 10;
  227         /* never automatically crank down to less */
  228 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_RTMINEXPIRE, rtminexpire,
  229         CTLFLAG_RW, &rtq_minreallyold , 0, "");
  230 
  231 static int rtq_toomany = 128;
  232         /* 128 cached routes is ``too many'' */
  233 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_RTMAXCACHE, rtmaxcache,
  234         CTLFLAG_RW, &rtq_toomany , 0, "");
  235 
  236 
  237 /*
  238  * On last reference drop, mark the route as belong to us so that it can be
  239  * timed out.
  240  */
  241 static void
  242 in6_clsroute(struct radix_node *rn, struct radix_node_head *head)
  243 {
  244         struct rtentry *rt = (struct rtentry *)rn;
  245 
  246         RT_LOCK_ASSERT(rt);
  247 
  248         if (!(rt->rt_flags & RTF_UP))
  249                 return;         /* prophylactic measures */
  250 
  251         if ((rt->rt_flags & (RTF_LLINFO | RTF_HOST)) != RTF_HOST)
  252                 return;
  253 
  254         if ((rt->rt_flags & (RTF_WASCLONED | RTPRF_OURS)) != RTF_WASCLONED)
  255                 return;
  256 
  257         /*
  258          * As requested by David Greenman:
  259          * If rtq_reallyold is 0, just delete the route without
  260          * waiting for a timeout cycle to kill it.
  261          */
  262         if (rtq_reallyold != 0) {
  263                 rt->rt_flags |= RTPRF_OURS;
  264                 rt->rt_rmx.rmx_expire = time_uptime + rtq_reallyold;
  265         } else {
  266                 rtexpunge(rt);
  267         }
  268 }
  269 
  270 struct rtqk_arg {
  271         struct radix_node_head *rnh;
  272         int mode;
  273         int updating;
  274         int draining;
  275         int killed;
  276         int found;
  277         time_t nextstop;
  278 };
  279 
  280 /*
  281  * Get rid of old routes.  When draining, this deletes everything, even when
  282  * the timeout is not expired yet.  When updating, this makes sure that
  283  * nothing has a timeout longer than the current value of rtq_reallyold.
  284  */
  285 static int
  286 in6_rtqkill(struct radix_node *rn, void *rock)
  287 {
  288         struct rtqk_arg *ap = rock;
  289         struct rtentry *rt = (struct rtentry *)rn;
  290         int err;
  291 
  292         RADIX_NODE_HEAD_LOCK_ASSERT(ap->rnh);
  293 
  294         if (rt->rt_flags & RTPRF_OURS) {
  295                 ap->found++;
  296 
  297                 if (ap->draining || rt->rt_rmx.rmx_expire <= time_uptime) {
  298                         if (rt->rt_refcnt > 0)
  299                                 panic("rtqkill route really not free");
  300 
  301                         err = rtrequest(RTM_DELETE,
  302                                         (struct sockaddr *)rt_key(rt),
  303                                         rt->rt_gateway, rt_mask(rt),
  304                                         rt->rt_flags|RTF_RNH_LOCKED, 0);
  305                         if (err) {
  306                                 log(LOG_WARNING, "in6_rtqkill: error %d", err);
  307                         } else {
  308                                 ap->killed++;
  309                         }
  310                 } else {
  311                         if (ap->updating
  312                            && (rt->rt_rmx.rmx_expire - time_uptime
  313                                > rtq_reallyold)) {
  314                                 rt->rt_rmx.rmx_expire = time_uptime
  315                                         + rtq_reallyold;
  316                         }
  317                         ap->nextstop = lmin(ap->nextstop,
  318                                             rt->rt_rmx.rmx_expire);
  319                 }
  320         }
  321 
  322         return 0;
  323 }
  324 
  325 #define RTQ_TIMEOUT     60*10   /* run no less than once every ten minutes */
  326 static int rtq_timeout = RTQ_TIMEOUT;
  327 static struct callout rtq_timer;
  328 
  329 static void
  330 in6_rtqtimo(void *rock)
  331 {
  332         struct radix_node_head *rnh = rock;
  333         struct rtqk_arg arg;
  334         struct timeval atv;
  335         static time_t last_adjusted_timeout = 0;
  336 
  337         arg.found = arg.killed = 0;
  338         arg.rnh = rnh;
  339         arg.nextstop = time_uptime + rtq_timeout;
  340         arg.draining = arg.updating = 0;
  341         RADIX_NODE_HEAD_LOCK(rnh);
  342         rnh->rnh_walktree(rnh, in6_rtqkill, &arg);
  343         RADIX_NODE_HEAD_UNLOCK(rnh);
  344 
  345         /*
  346          * Attempt to be somewhat dynamic about this:
  347          * If there are ``too many'' routes sitting around taking up space,
  348          * then crank down the timeout, and see if we can't make some more
  349          * go away.  However, we make sure that we will never adjust more
  350          * than once in rtq_timeout seconds, to keep from cranking down too
  351          * hard.
  352          */
  353         if ((arg.found - arg.killed > rtq_toomany)
  354            && (time_uptime - last_adjusted_timeout >= rtq_timeout)
  355            && rtq_reallyold > rtq_minreallyold) {
  356                 rtq_reallyold = 2*rtq_reallyold / 3;
  357                 if (rtq_reallyold < rtq_minreallyold) {
  358                         rtq_reallyold = rtq_minreallyold;
  359                 }
  360 
  361                 last_adjusted_timeout = time_uptime;
  362 #ifdef DIAGNOSTIC
  363                 log(LOG_DEBUG, "in6_rtqtimo: adjusted rtq_reallyold to %d",
  364                     rtq_reallyold);
  365 #endif
  366                 arg.found = arg.killed = 0;
  367                 arg.updating = 1;
  368                 RADIX_NODE_HEAD_LOCK(rnh);
  369                 rnh->rnh_walktree(rnh, in6_rtqkill, &arg);
  370                 RADIX_NODE_HEAD_UNLOCK(rnh);
  371         }
  372 
  373         atv.tv_usec = 0;
  374         atv.tv_sec = arg.nextstop - time_uptime;
  375         callout_reset(&rtq_timer, tvtohz(&atv), in6_rtqtimo, rock);
  376 }
  377 
  378 /*
  379  * Age old PMTUs.
  380  */
  381 struct mtuex_arg {
  382         struct radix_node_head *rnh;
  383         time_t nextstop;
  384 };
  385 static struct callout rtq_mtutimer;
  386 
  387 static int
  388 in6_mtuexpire(struct radix_node *rn, void *rock)
  389 {
  390         struct rtentry *rt = (struct rtentry *)rn;
  391         struct mtuex_arg *ap = rock;
  392 
  393         /* sanity */
  394         if (!rt)
  395                 panic("rt == NULL in in6_mtuexpire");
  396 
  397         if (rt->rt_rmx.rmx_expire && !(rt->rt_flags & RTF_PROBEMTU)) {
  398                 if (rt->rt_rmx.rmx_expire <= time_uptime) {
  399                         rt->rt_flags |= RTF_PROBEMTU;
  400                 } else {
  401                         ap->nextstop = lmin(ap->nextstop,
  402                                         rt->rt_rmx.rmx_expire);
  403                 }
  404         }
  405 
  406         return 0;
  407 }
  408 
  409 #define MTUTIMO_DEFAULT (60*1)
  410 
  411 static void
  412 in6_mtutimo(void *rock)
  413 {
  414         struct radix_node_head *rnh = rock;
  415         struct mtuex_arg arg;
  416         struct timeval atv;
  417 
  418         arg.rnh = rnh;
  419         arg.nextstop = time_uptime + MTUTIMO_DEFAULT;
  420         RADIX_NODE_HEAD_LOCK(rnh);
  421         rnh->rnh_walktree(rnh, in6_mtuexpire, &arg);
  422         RADIX_NODE_HEAD_UNLOCK(rnh);
  423 
  424         atv.tv_usec = 0;
  425         atv.tv_sec = arg.nextstop - time_uptime;
  426         if (atv.tv_sec < 0) {
  427                 printf("invalid mtu expiration time on routing table\n");
  428                 arg.nextstop = time_uptime + 30;        /* last resort */
  429                 atv.tv_sec = 30;
  430         }
  431         callout_reset(&rtq_mtutimer, tvtohz(&atv), in6_mtutimo, rock);
  432 }
  433 
  434 #if 0
  435 void
  436 in6_rtqdrain(void)
  437 {
  438         struct radix_node_head *rnh = rt_tables[AF_INET6];
  439         struct rtqk_arg arg;
  440 
  441         arg.found = arg.killed = 0;
  442         arg.rnh = rnh;
  443         arg.nextstop = 0;
  444         arg.draining = 1;
  445         arg.updating = 0;
  446         RADIX_NODE_HEAD_LOCK(rnh);
  447         rnh->rnh_walktree(rnh, in6_rtqkill, &arg);
  448         RADIX_NODE_HEAD_UNLOCK(rnh);
  449 }
  450 #endif
  451 
  452 /*
  453  * Initialize our routing tree.
  454  * XXX MRT When off == 0, we are being called from vfs_export.c
  455  * so just set up their table and leave. (we know what the correct
  456  * value should be so just use that).. FIX AFTER RELENG_7 is MFC'd
  457  * see also comments in in_inithead() vfs_export.c and domain.h
  458  */
  459 int
  460 in6_inithead(void **head, int off)
  461 {
  462         struct radix_node_head *rnh;
  463 
  464         if (!rn_inithead(head, offsetof(struct sockaddr_in6, sin6_addr) << 3))
  465                 return 0;               /* See above */
  466 
  467         if (off == 0)           /* See above */
  468                 return 1;       /* only do the rest for the real thing */
  469 
  470         rnh = *head;
  471         rnh->rnh_addaddr = in6_addroute;
  472         rnh->rnh_matchaddr = in6_matroute;
  473         rnh->rnh_close = in6_clsroute;
  474         callout_init(&rtq_timer, CALLOUT_MPSAFE);
  475         in6_rtqtimo(rnh);       /* kick off timeout first time */
  476         callout_init(&rtq_mtutimer, CALLOUT_MPSAFE);
  477         in6_mtutimo(rnh);       /* kick off timeout first time */
  478         return 1;
  479 }

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