The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netinet/in_rmx.c

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    1 /*-
    2  * Copyright 1994, 1995 Massachusetts Institute of Technology
    3  *
    4  * Permission to use, copy, modify, and distribute this software and
    5  * its documentation for any purpose and without fee is hereby
    6  * granted, provided that both the above copyright notice and this
    7  * permission notice appear in all copies, that both the above
    8  * copyright notice and this permission notice appear in all
    9  * supporting documentation, and that the name of M.I.T. not be used
   10  * in advertising or publicity pertaining to distribution of the
   11  * software without specific, written prior permission.  M.I.T. makes
   12  * no representations about the suitability of this software for any
   13  * purpose.  It is provided "as is" without express or implied
   14  * warranty.
   15  *
   16  * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''.  M.I.T. DISCLAIMS
   17  * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
   18  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
   20  * SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   23  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   24  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   25  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   26  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  */
   29 
   30 /*
   31  * This code does two things necessary for the enhanced TCP metrics to
   32  * function in a useful manner:
   33  *  1) It marks all non-host routes as `cloning', thus ensuring that
   34  *     every actual reference to such a route actually gets turned
   35  *     into a reference to a host route to the specific destination
   36  *     requested.
   37  *  2) When such routes lose all their references, it arranges for them
   38  *     to be deleted in some random collection of circumstances, so that
   39  *     a large quantity of stale routing data is not kept in kernel memory
   40  *     indefinitely.  See in_rtqtimo() below for the exact mechanism.
   41  */
   42 
   43 #include <sys/cdefs.h>
   44 __FBSDID("$FreeBSD: releng/8.1/sys/netinet/in_rmx.c 207695 2010-05-06 06:44:19Z bz $");
   45 
   46 #include <sys/param.h>
   47 #include <sys/systm.h>
   48 #include <sys/kernel.h>
   49 #include <sys/sysctl.h>
   50 #include <sys/socket.h>
   51 #include <sys/mbuf.h>
   52 #include <sys/syslog.h>
   53 #include <sys/callout.h>
   54 
   55 #include <net/if.h>
   56 #include <net/route.h>
   57 #include <net/vnet.h>
   58 
   59 #include <netinet/in.h>
   60 #include <netinet/in_var.h>
   61 #include <netinet/ip_var.h>
   62 
   63 extern int      in_inithead(void **head, int off);
   64 #ifdef VIMAGE
   65 extern int      in_detachhead(void **head, int off);
   66 #endif
   67 
   68 #define RTPRF_OURS              RTF_PROTO3      /* set on routes we manage */
   69 
   70 /*
   71  * Do what we need to do when inserting a route.
   72  */
   73 static struct radix_node *
   74 in_addroute(void *v_arg, void *n_arg, struct radix_node_head *head,
   75     struct radix_node *treenodes)
   76 {
   77         struct rtentry *rt = (struct rtentry *)treenodes;
   78         struct sockaddr_in *sin = (struct sockaddr_in *)rt_key(rt);
   79 
   80         RADIX_NODE_HEAD_WLOCK_ASSERT(head);
   81         /*
   82          * A little bit of help for both IP output and input:
   83          *   For host routes, we make sure that RTF_BROADCAST
   84          *   is set for anything that looks like a broadcast address.
   85          *   This way, we can avoid an expensive call to in_broadcast()
   86          *   in ip_output() most of the time (because the route passed
   87          *   to ip_output() is almost always a host route).
   88          *
   89          *   We also do the same for local addresses, with the thought
   90          *   that this might one day be used to speed up ip_input().
   91          *
   92          * We also mark routes to multicast addresses as such, because
   93          * it's easy to do and might be useful (but this is much more
   94          * dubious since it's so easy to inspect the address).
   95          */
   96         if (rt->rt_flags & RTF_HOST) {
   97                 if (in_broadcast(sin->sin_addr, rt->rt_ifp)) {
   98                         rt->rt_flags |= RTF_BROADCAST;
   99                 } else if (satosin(rt->rt_ifa->ifa_addr)->sin_addr.s_addr ==
  100                     sin->sin_addr.s_addr) {
  101                         rt->rt_flags |= RTF_LOCAL;
  102                 }
  103         }
  104         if (IN_MULTICAST(ntohl(sin->sin_addr.s_addr)))
  105                 rt->rt_flags |= RTF_MULTICAST;
  106 
  107         if (!rt->rt_rmx.rmx_mtu && rt->rt_ifp)
  108                 rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu;
  109 
  110         return (rn_addroute(v_arg, n_arg, head, treenodes));
  111 }
  112 
  113 /*
  114  * This code is the inverse of in_clsroute: on first reference, if we
  115  * were managing the route, stop doing so and set the expiration timer
  116  * back off again.
  117  */
  118 static struct radix_node *
  119 in_matroute(void *v_arg, struct radix_node_head *head)
  120 {
  121         struct radix_node *rn = rn_match(v_arg, head);
  122         struct rtentry *rt = (struct rtentry *)rn;
  123 
  124         /*XXX locking? */
  125         if (rt && rt->rt_refcnt == 0) {         /* this is first reference */
  126                 if (rt->rt_flags & RTPRF_OURS) {
  127                         rt->rt_flags &= ~RTPRF_OURS;
  128                         rt->rt_rmx.rmx_expire = 0;
  129                 }
  130         }
  131         return rn;
  132 }
  133 
  134 static VNET_DEFINE(int, rtq_reallyold) = 60*60; /* one hour is "really old" */
  135 #define V_rtq_reallyold         VNET(rtq_reallyold)
  136 SYSCTL_VNET_INT(_net_inet_ip, IPCTL_RTEXPIRE, rtexpire, CTLFLAG_RW,
  137     &VNET_NAME(rtq_reallyold), 0,
  138     "Default expiration time on dynamically learned routes");
  139 
  140 /* never automatically crank down to less */
  141 static VNET_DEFINE(int, rtq_minreallyold) = 10;
  142 #define V_rtq_minreallyold      VNET(rtq_minreallyold)
  143 SYSCTL_VNET_INT(_net_inet_ip, IPCTL_RTMINEXPIRE, rtminexpire, CTLFLAG_RW,
  144     &VNET_NAME(rtq_minreallyold), 0,
  145     "Minimum time to attempt to hold onto dynamically learned routes");
  146 
  147 /* 128 cached routes is "too many" */
  148 static VNET_DEFINE(int, rtq_toomany) = 128;
  149 #define V_rtq_toomany           VNET(rtq_toomany)
  150 SYSCTL_VNET_INT(_net_inet_ip, IPCTL_RTMAXCACHE, rtmaxcache, CTLFLAG_RW,
  151     &VNET_NAME(rtq_toomany), 0,
  152     "Upper limit on dynamically learned routes");
  153 
  154 /*
  155  * On last reference drop, mark the route as belong to us so that it can be
  156  * timed out.
  157  */
  158 static void
  159 in_clsroute(struct radix_node *rn, struct radix_node_head *head)
  160 {
  161         struct rtentry *rt = (struct rtentry *)rn;
  162 
  163         RT_LOCK_ASSERT(rt);
  164 
  165         if (!(rt->rt_flags & RTF_UP))
  166                 return;                 /* prophylactic measures */
  167 
  168         if (rt->rt_flags & RTPRF_OURS)
  169                 return;
  170 
  171         if (!(rt->rt_flags & RTF_DYNAMIC))
  172                 return;
  173 
  174         /*
  175          * If rtq_reallyold is 0, just delete the route without
  176          * waiting for a timeout cycle to kill it.
  177          */
  178         if (V_rtq_reallyold != 0) {
  179                 rt->rt_flags |= RTPRF_OURS;
  180                 rt->rt_rmx.rmx_expire = time_uptime + V_rtq_reallyold;
  181         } else {
  182                 rtexpunge(rt);
  183         }
  184 }
  185 
  186 struct rtqk_arg {
  187         struct radix_node_head *rnh;
  188         int draining;
  189         int killed;
  190         int found;
  191         int updating;
  192         time_t nextstop;
  193 };
  194 
  195 /*
  196  * Get rid of old routes.  When draining, this deletes everything, even when
  197  * the timeout is not expired yet.  When updating, this makes sure that
  198  * nothing has a timeout longer than the current value of rtq_reallyold.
  199  */
  200 static int
  201 in_rtqkill(struct radix_node *rn, void *rock)
  202 {
  203         struct rtqk_arg *ap = rock;
  204         struct rtentry *rt = (struct rtentry *)rn;
  205         int err;
  206 
  207         RADIX_NODE_HEAD_WLOCK_ASSERT(ap->rnh);
  208 
  209         if (rt->rt_flags & RTPRF_OURS) {
  210                 ap->found++;
  211 
  212                 if (ap->draining || rt->rt_rmx.rmx_expire <= time_uptime) {
  213                         if (rt->rt_refcnt > 0)
  214                                 panic("rtqkill route really not free");
  215 
  216                         err = in_rtrequest(RTM_DELETE,
  217                                         (struct sockaddr *)rt_key(rt),
  218                                         rt->rt_gateway, rt_mask(rt),
  219                                         rt->rt_flags | RTF_RNH_LOCKED, 0,
  220                                         rt->rt_fibnum);
  221                         if (err) {
  222                                 log(LOG_WARNING, "in_rtqkill: error %d\n", err);
  223                         } else {
  224                                 ap->killed++;
  225                         }
  226                 } else {
  227                         if (ap->updating &&
  228                             (rt->rt_rmx.rmx_expire - time_uptime >
  229                              V_rtq_reallyold)) {
  230                                 rt->rt_rmx.rmx_expire =
  231                                     time_uptime + V_rtq_reallyold;
  232                         }
  233                         ap->nextstop = lmin(ap->nextstop,
  234                                             rt->rt_rmx.rmx_expire);
  235                 }
  236         }
  237 
  238         return 0;
  239 }
  240 
  241 #define RTQ_TIMEOUT     60*10   /* run no less than once every ten minutes */
  242 static VNET_DEFINE(int, rtq_timeout) = RTQ_TIMEOUT;
  243 static VNET_DEFINE(struct callout, rtq_timer);
  244 
  245 #define V_rtq_timeout           VNET(rtq_timeout)
  246 #define V_rtq_timer             VNET(rtq_timer)
  247 
  248 static void in_rtqtimo_one(void *rock);
  249 
  250 static void
  251 in_rtqtimo(void *rock)
  252 {
  253         CURVNET_SET((struct vnet *) rock);
  254         int fibnum;
  255         void *newrock;
  256         struct timeval atv;
  257 
  258         for (fibnum = 0; fibnum < rt_numfibs; fibnum++) {
  259                 newrock = rt_tables_get_rnh(fibnum, AF_INET);
  260                 if (newrock != NULL)
  261                         in_rtqtimo_one(newrock);
  262         }
  263         atv.tv_usec = 0;
  264         atv.tv_sec = V_rtq_timeout;
  265         callout_reset(&V_rtq_timer, tvtohz(&atv), in_rtqtimo, rock);
  266         CURVNET_RESTORE();
  267 }
  268 
  269 static void
  270 in_rtqtimo_one(void *rock)
  271 {
  272         struct radix_node_head *rnh = rock;
  273         struct rtqk_arg arg;
  274         static time_t last_adjusted_timeout = 0;
  275 
  276         arg.found = arg.killed = 0;
  277         arg.rnh = rnh;
  278         arg.nextstop = time_uptime + V_rtq_timeout;
  279         arg.draining = arg.updating = 0;
  280         RADIX_NODE_HEAD_LOCK(rnh);
  281         rnh->rnh_walktree(rnh, in_rtqkill, &arg);
  282         RADIX_NODE_HEAD_UNLOCK(rnh);
  283 
  284         /*
  285          * Attempt to be somewhat dynamic about this:
  286          * If there are ``too many'' routes sitting around taking up space,
  287          * then crank down the timeout, and see if we can't make some more
  288          * go away.  However, we make sure that we will never adjust more
  289          * than once in rtq_timeout seconds, to keep from cranking down too
  290          * hard.
  291          */
  292         if ((arg.found - arg.killed > V_rtq_toomany) &&
  293             (time_uptime - last_adjusted_timeout >= V_rtq_timeout) &&
  294             V_rtq_reallyold > V_rtq_minreallyold) {
  295                 V_rtq_reallyold = 2 * V_rtq_reallyold / 3;
  296                 if (V_rtq_reallyold < V_rtq_minreallyold) {
  297                         V_rtq_reallyold = V_rtq_minreallyold;
  298                 }
  299 
  300                 last_adjusted_timeout = time_uptime;
  301 #ifdef DIAGNOSTIC
  302                 log(LOG_DEBUG, "in_rtqtimo: adjusted rtq_reallyold to %d\n",
  303                     V_rtq_reallyold);
  304 #endif
  305                 arg.found = arg.killed = 0;
  306                 arg.updating = 1;
  307                 RADIX_NODE_HEAD_LOCK(rnh);
  308                 rnh->rnh_walktree(rnh, in_rtqkill, &arg);
  309                 RADIX_NODE_HEAD_UNLOCK(rnh);
  310         }
  311 
  312 }
  313 
  314 void
  315 in_rtqdrain(void)
  316 {
  317         VNET_ITERATOR_DECL(vnet_iter);
  318         struct radix_node_head *rnh;
  319         struct rtqk_arg arg;
  320         int     fibnum;
  321 
  322         VNET_LIST_RLOCK_NOSLEEP();
  323         VNET_FOREACH(vnet_iter) {
  324                 CURVNET_SET(vnet_iter);
  325 
  326                 for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
  327                         rnh = rt_tables_get_rnh(fibnum, AF_INET);
  328                         arg.found = arg.killed = 0;
  329                         arg.rnh = rnh;
  330                         arg.nextstop = 0;
  331                         arg.draining = 1;
  332                         arg.updating = 0;
  333                         RADIX_NODE_HEAD_LOCK(rnh);
  334                         rnh->rnh_walktree(rnh, in_rtqkill, &arg);
  335                         RADIX_NODE_HEAD_UNLOCK(rnh);
  336                 }
  337                 CURVNET_RESTORE();
  338         }
  339         VNET_LIST_RUNLOCK_NOSLEEP();
  340 }
  341 
  342 static int _in_rt_was_here;
  343 /*
  344  * Initialize our routing tree.
  345  */
  346 int
  347 in_inithead(void **head, int off)
  348 {
  349         struct radix_node_head *rnh;
  350 
  351         /* XXX MRT
  352          * This can be called from vfs_export.c too in which case 'off'
  353          * will be 0. We know the correct value so just use that and
  354          * return directly if it was 0.
  355          * This is a hack that replaces an even worse hack on a bad hack
  356          * on a bad design. After RELENG_7 this should be fixed but that
  357          * will change the ABI, so for now do it this way.
  358          */
  359         if (!rn_inithead(head, 32))
  360                 return 0;
  361 
  362         if (off == 0)           /* XXX MRT  see above */
  363                 return 1;       /* only do the rest for a real routing table */
  364 
  365         rnh = *head;
  366         rnh->rnh_addaddr = in_addroute;
  367         rnh->rnh_matchaddr = in_matroute;
  368         rnh->rnh_close = in_clsroute;
  369         if (_in_rt_was_here == 0 ) {
  370                 callout_init(&V_rtq_timer, CALLOUT_MPSAFE);
  371                 callout_reset(&V_rtq_timer, 1, in_rtqtimo, curvnet);
  372                 _in_rt_was_here = 1;
  373         }
  374         return 1;
  375 }
  376 
  377 #ifdef VIMAGE
  378 int
  379 in_detachhead(void **head, int off)
  380 {
  381 
  382         callout_drain(&V_rtq_timer);
  383         return (1);
  384 }
  385 #endif
  386 
  387 /*
  388  * This zaps old routes when the interface goes down or interface
  389  * address is deleted.  In the latter case, it deletes static routes
  390  * that point to this address.  If we don't do this, we may end up
  391  * using the old address in the future.  The ones we always want to
  392  * get rid of are things like ARP entries, since the user might down
  393  * the interface, walk over to a completely different network, and
  394  * plug back in.
  395  */
  396 struct in_ifadown_arg {
  397         struct ifaddr *ifa;
  398         int del;
  399 };
  400 
  401 static int
  402 in_ifadownkill(struct radix_node *rn, void *xap)
  403 {
  404         struct in_ifadown_arg *ap = xap;
  405         struct rtentry *rt = (struct rtentry *)rn;
  406 
  407         RT_LOCK(rt);
  408         if (rt->rt_ifa == ap->ifa &&
  409             (ap->del || !(rt->rt_flags & RTF_STATIC))) {
  410                 /*
  411                  * We need to disable the automatic prune that happens
  412                  * in this case in rtrequest() because it will blow
  413                  * away the pointers that rn_walktree() needs in order
  414                  * continue our descent.  We will end up deleting all
  415                  * the routes that rtrequest() would have in any case,
  416                  * so that behavior is not needed there.
  417                  */
  418                 rtexpunge(rt);
  419         }
  420         RT_UNLOCK(rt);
  421         return 0;
  422 }
  423 
  424 int
  425 in_ifadown(struct ifaddr *ifa, int delete)
  426 {
  427         struct in_ifadown_arg arg;
  428         struct radix_node_head *rnh;
  429         int     fibnum;
  430 
  431         if (ifa->ifa_addr->sa_family != AF_INET)
  432                 return 1;
  433 
  434         for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
  435                 rnh = rt_tables_get_rnh(fibnum, AF_INET);
  436                 arg.ifa = ifa;
  437                 arg.del = delete;
  438                 RADIX_NODE_HEAD_LOCK(rnh);
  439                 rnh->rnh_walktree(rnh, in_ifadownkill, &arg);
  440                 RADIX_NODE_HEAD_UNLOCK(rnh);
  441                 ifa->ifa_flags &= ~IFA_ROUTE;           /* XXXlocking? */
  442         }
  443         return 0;
  444 }
  445 
  446 /*
  447  * inet versions of rt functions. These have fib extensions and 
  448  * for now will just reference the _fib variants.
  449  * eventually this order will be reversed,
  450  */
  451 void
  452 in_rtalloc_ign(struct route *ro, u_long ignflags, u_int fibnum)
  453 {
  454         rtalloc_ign_fib(ro, ignflags, fibnum);
  455 }
  456 
  457 int
  458 in_rtrequest( int req,
  459         struct sockaddr *dst,
  460         struct sockaddr *gateway,
  461         struct sockaddr *netmask,
  462         int flags,
  463         struct rtentry **ret_nrt,
  464         u_int fibnum)
  465 {
  466         return (rtrequest_fib(req, dst, gateway, netmask, 
  467             flags, ret_nrt, fibnum));
  468 }
  469 
  470 struct rtentry *
  471 in_rtalloc1(struct sockaddr *dst, int report, u_long ignflags, u_int fibnum)
  472 {
  473         return (rtalloc1_fib(dst, report, ignflags, fibnum));
  474 }
  475 
  476 void
  477 in_rtredirect(struct sockaddr *dst,
  478         struct sockaddr *gateway,
  479         struct sockaddr *netmask,
  480         int flags,
  481         struct sockaddr *src,
  482         u_int fibnum)
  483 {
  484         rtredirect_fib(dst, gateway, netmask, flags, src, fibnum);
  485 }
  486  
  487 void
  488 in_rtalloc(struct route *ro, u_int fibnum)
  489 {
  490         rtalloc_ign_fib(ro, 0UL, fibnum);
  491 }
  492 
  493 #if 0
  494 int      in_rt_getifa(struct rt_addrinfo *, u_int fibnum);
  495 int      in_rtioctl(u_long, caddr_t, u_int);
  496 int      in_rtrequest1(int, struct rt_addrinfo *, struct rtentry **, u_int);
  497 #endif
  498 
  499 

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