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 * $FreeBSD: src/sys/netinet/in_rmx.c,v 1.37.2.3 2002/08/09 14:49:23 ru Exp $ 30 * $DragonFly: src/sys/netinet/in_rmx.c,v 1.6 2004/12/14 18:46:08 hsu Exp $ 31 */ 32 33 /* 34 * This code does two things necessary for the enhanced TCP metrics to 35 * function in a useful manner: 36 * 1) It marks all non-host routes as `cloning', thus ensuring that 37 * every actual reference to such a route actually gets turned 38 * into a reference to a host route to the specific destination 39 * requested. 40 * 2) When such routes lose all their references, it arranges for them 41 * to be deleted in some random collection of circumstances, so that 42 * a large quantity of stale routing data is not kept in kernel memory 43 * indefinitely. See in_rtqtimo() below for the exact mechanism. 44 */ 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 54 #include <net/if.h> 55 #include <net/route.h> 56 #include <netinet/in.h> 57 #include <netinet/in_var.h> 58 #include <netinet/ip_var.h> 59 60 #define RTPRF_OURS RTF_PROTO3 /* set on routes we manage */ 61 62 static struct callout in_rtqtimo_ch; 63 64 /* 65 * Do what we need to do when inserting a route. 66 */ 67 static struct radix_node * 68 in_addroute(char *key, char *mask, struct radix_node_head *head, 69 struct radix_node *treenodes) 70 { 71 struct rtentry *rt = (struct rtentry *)treenodes; 72 struct sockaddr_in *sin = (struct sockaddr_in *)rt_key(rt); 73 struct radix_node *ret; 74 75 /* 76 * For IP, all unicast non-host routes are automatically cloning. 77 */ 78 if (IN_MULTICAST(ntohl(sin->sin_addr.s_addr))) 79 rt->rt_flags |= RTF_MULTICAST; 80 81 if (!(rt->rt_flags & (RTF_HOST | RTF_CLONING | RTF_MULTICAST))) { 82 rt->rt_flags |= RTF_PRCLONING; 83 } 84 85 /* 86 * A little bit of help for both IP output and input: 87 * For host routes, we make sure that RTF_BROADCAST 88 * is set for anything that looks like a broadcast address. 89 * This way, we can avoid an expensive call to in_broadcast() 90 * in ip_output() most of the time (because the route passed 91 * to ip_output() is almost always a host route). 92 * 93 * We also do the same for local addresses, with the thought 94 * that this might one day be used to speed up ip_input(). 95 * 96 * We also mark routes to multicast addresses as such, because 97 * it's easy to do and might be useful (but this is much more 98 * dubious since it's so easy to inspect the address). (This 99 * is done above.) 100 */ 101 if (rt->rt_flags & RTF_HOST) { 102 if (in_broadcast(sin->sin_addr, rt->rt_ifp)) { 103 rt->rt_flags |= RTF_BROADCAST; 104 } else { 105 if (satosin(rt->rt_ifa->ifa_addr)->sin_addr.s_addr 106 == sin->sin_addr.s_addr) 107 rt->rt_flags |= RTF_LOCAL; 108 } 109 } 110 111 if (rt->rt_rmx.rmx_mtu != 0 && !(rt->rt_rmx.rmx_locks & RTV_MTU) && 112 rt->rt_ifp != NULL) 113 rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu; 114 115 ret = rn_addroute(key, mask, head, treenodes); 116 if (ret == NULL && rt->rt_flags & RTF_HOST) { 117 struct rtentry *rt2; 118 /* 119 * We are trying to add a host route, but can't. 120 * Find out if it is because of an 121 * ARP entry and delete it if so. 122 */ 123 rt2 = rtalloc1((struct sockaddr *)sin, 0, 124 RTF_CLONING | RTF_PRCLONING); 125 if (rt2) { 126 if (rt2->rt_flags & RTF_LLINFO && 127 rt2->rt_flags & RTF_HOST && 128 rt2->rt_gateway && 129 rt2->rt_gateway->sa_family == AF_LINK) { 130 rtrequest(RTM_DELETE, 131 (struct sockaddr *)rt_key(rt2), 132 rt2->rt_gateway, 133 rt_mask(rt2), rt2->rt_flags, 0); 134 ret = rn_addroute(key, mask, head, 135 treenodes); 136 } 137 RTFREE(rt2); 138 } 139 } 140 141 /* 142 * If the new route created successfully, and we are forwarding, 143 * and there is a cached route, free it. Otherwise, we may end 144 * up using the wrong route. 145 */ 146 if (ret != NULL && ipforwarding && ipforward_rt.ro_rt != NULL) { 147 RTFREE(ipforward_rt.ro_rt); 148 ipforward_rt.ro_rt = NULL; 149 } 150 151 return ret; 152 } 153 154 /* 155 * This code is the inverse of in_clsroute: on first reference, if we 156 * were managing the route, stop doing so and set the expiration timer 157 * back off again. 158 */ 159 static struct radix_node * 160 in_matchroute(char *key, struct radix_node_head *head) 161 { 162 struct radix_node *rn = rn_match(key, head); 163 struct rtentry *rt = (struct rtentry *)rn; 164 165 if (rt != NULL && rt->rt_refcnt == 0) { /* this is first reference */ 166 if (rt->rt_flags & RTPRF_OURS) { 167 rt->rt_flags &= ~RTPRF_OURS; 168 rt->rt_rmx.rmx_expire = 0; 169 } 170 } 171 return rn; 172 } 173 174 static int rtq_reallyold = 60*60; /* one hour is ``really old'' */ 175 SYSCTL_INT(_net_inet_ip, IPCTL_RTEXPIRE, rtexpire, CTLFLAG_RW, 176 &rtq_reallyold , 0, 177 "Default expiration time on dynamically learned routes"); 178 179 static int rtq_minreallyold = 10; /* never automatically crank down to less */ 180 SYSCTL_INT(_net_inet_ip, IPCTL_RTMINEXPIRE, rtminexpire, CTLFLAG_RW, 181 &rtq_minreallyold , 0, 182 "Minimum time to attempt to hold onto dynamically learned routes"); 183 184 static int rtq_toomany = 128; /* 128 cached routes is ``too many'' */ 185 SYSCTL_INT(_net_inet_ip, IPCTL_RTMAXCACHE, rtmaxcache, CTLFLAG_RW, 186 &rtq_toomany , 0, "Upper limit on dynamically learned routes"); 187 188 /* 189 * On last reference drop, mark the route as belong to us so that it can be 190 * timed out. 191 */ 192 static void 193 in_clsroute(struct radix_node *rn, struct radix_node_head *head) 194 { 195 struct rtentry *rt = (struct rtentry *)rn; 196 197 if (!(rt->rt_flags & RTF_UP)) 198 return; /* prophylactic measures */ 199 200 if ((rt->rt_flags & (RTF_LLINFO | RTF_HOST)) != RTF_HOST) 201 return; 202 203 if ((rt->rt_flags & (RTF_WASCLONED | RTPRF_OURS)) != RTF_WASCLONED) 204 return; 205 206 /* 207 * As requested by David Greenman: 208 * If rtq_reallyold is 0, just delete the route without 209 * waiting for a timeout cycle to kill it. 210 */ 211 if (rtq_reallyold != 0) { 212 rt->rt_flags |= RTPRF_OURS; 213 rt->rt_rmx.rmx_expire = time_second + rtq_reallyold; 214 } else { 215 rtrequest(RTM_DELETE, 216 (struct sockaddr *)rt_key(rt), 217 rt->rt_gateway, rt_mask(rt), 218 rt->rt_flags, 0); 219 } 220 } 221 222 struct rtqk_arg { 223 struct radix_node_head *rnh; 224 int draining; 225 int killed; 226 int found; 227 int updating; 228 time_t nextstop; 229 }; 230 231 /* 232 * Get rid of old routes. When draining, this deletes everything, even when 233 * the timeout is not expired yet. When updating, this makes sure that 234 * nothing has a timeout longer than the current value of rtq_reallyold. 235 */ 236 static int 237 in_rtqkill(struct radix_node *rn, void *rock) 238 { 239 struct rtqk_arg *ap = rock; 240 struct rtentry *rt = (struct rtentry *)rn; 241 int err; 242 243 if (rt->rt_flags & RTPRF_OURS) { 244 ap->found++; 245 246 if (ap->draining || rt->rt_rmx.rmx_expire <= time_second) { 247 if (rt->rt_refcnt > 0) 248 panic("rtqkill route really not free"); 249 250 err = rtrequest(RTM_DELETE, 251 (struct sockaddr *)rt_key(rt), 252 rt->rt_gateway, rt_mask(rt), 253 rt->rt_flags, 0); 254 if (err) { 255 log(LOG_WARNING, "in_rtqkill: error %d\n", err); 256 } else { 257 ap->killed++; 258 } 259 } else { 260 if (ap->updating && 261 (rt->rt_rmx.rmx_expire - time_second > 262 rtq_reallyold)) { 263 rt->rt_rmx.rmx_expire = time_second + 264 rtq_reallyold; 265 } 266 ap->nextstop = lmin(ap->nextstop, 267 rt->rt_rmx.rmx_expire); 268 } 269 } 270 271 return 0; 272 } 273 274 #define RTQ_TIMEOUT 60*10 /* run no less than once every ten minutes */ 275 static int rtq_timeout = RTQ_TIMEOUT; 276 277 static void 278 in_rtqtimo(void *rock) 279 { 280 struct radix_node_head *rnh = rock; 281 struct rtqk_arg arg; 282 struct timeval atv; 283 static time_t last_adjusted_timeout = 0; 284 int s; 285 286 arg.found = arg.killed = 0; 287 arg.rnh = rnh; 288 arg.nextstop = time_second + rtq_timeout; 289 arg.draining = arg.updating = 0; 290 s = splnet(); 291 rnh->rnh_walktree(rnh, in_rtqkill, &arg); 292 splx(s); 293 294 /* 295 * Attempt to be somewhat dynamic about this: 296 * If there are ``too many'' routes sitting around taking up space, 297 * then crank down the timeout, and see if we can't make some more 298 * go away. However, we make sure that we will never adjust more 299 * than once in rtq_timeout seconds, to keep from cranking down too 300 * hard. 301 */ 302 if ((arg.found - arg.killed > rtq_toomany) && 303 (time_second - last_adjusted_timeout >= rtq_timeout) && 304 rtq_reallyold > rtq_minreallyold) { 305 rtq_reallyold = 2*rtq_reallyold / 3; 306 if (rtq_reallyold < rtq_minreallyold) { 307 rtq_reallyold = rtq_minreallyold; 308 } 309 310 last_adjusted_timeout = time_second; 311 #ifdef DIAGNOSTIC 312 log(LOG_DEBUG, "in_rtqtimo: adjusted rtq_reallyold to %d\n", 313 rtq_reallyold); 314 #endif 315 arg.found = arg.killed = 0; 316 arg.updating = 1; 317 s = splnet(); 318 rnh->rnh_walktree(rnh, in_rtqkill, &arg); 319 splx(s); 320 } 321 322 atv.tv_usec = 0; 323 atv.tv_sec = arg.nextstop - time_second; 324 callout_reset(&in_rtqtimo_ch, tvtohz_high(&atv), in_rtqtimo, rock); 325 } 326 327 void 328 in_rtqdrain(void) 329 { 330 struct radix_node_head *rnh = rt_tables[AF_INET]; 331 struct rtqk_arg arg; 332 int s; 333 334 arg.found = arg.killed = 0; 335 arg.rnh = rnh; 336 arg.nextstop = 0; 337 arg.draining = 1; 338 arg.updating = 0; 339 s = splnet(); 340 rnh->rnh_walktree(rnh, in_rtqkill, &arg); 341 splx(s); 342 } 343 344 /* 345 * Initialize our routing tree. 346 */ 347 int 348 in_inithead(void **head, int off) 349 { 350 struct radix_node_head *rnh; 351 352 if (!rn_inithead(head, off)) 353 return 0; 354 355 if (head != (void **)&rt_tables[AF_INET]) /* BOGUS! */ 356 return 1; /* only do this for the real routing table */ 357 358 rnh = *head; 359 rnh->rnh_addaddr = in_addroute; 360 rnh->rnh_matchaddr = in_matchroute; 361 rnh->rnh_close = in_clsroute; 362 callout_init(&in_rtqtimo_ch); 363 in_rtqtimo(rnh); /* kick off timeout first time */ 364 return 1; 365 } 366 367 368 /* 369 * This zaps old routes when the interface goes down or interface 370 * address is deleted. In the latter case, it deletes static routes 371 * that point to this address. If we don't do this, we may end up 372 * using the old address in the future. The ones we always want to 373 * get rid of are things like ARP entries, since the user might down 374 * the interface, walk over to a completely different network, and 375 * plug back in. 376 */ 377 struct in_ifadown_arg { 378 struct radix_node_head *rnh; 379 struct ifaddr *ifa; 380 int del; 381 }; 382 383 static int 384 in_ifadownkill(struct radix_node *rn, void *xap) 385 { 386 struct in_ifadown_arg *ap = xap; 387 struct rtentry *rt = (struct rtentry *)rn; 388 int err; 389 390 if (rt->rt_ifa == ap->ifa && 391 (ap->del || !(rt->rt_flags & RTF_STATIC))) { 392 /* 393 * We need to disable the automatic prune that happens 394 * in this case in rtrequest() because it will blow 395 * away the pointers that rn_walktree() needs in order 396 * continue our descent. We will end up deleting all 397 * the routes that rtrequest() would have in any case, 398 * so that behavior is not needed there. 399 */ 400 rt->rt_flags &= ~(RTF_CLONING | RTF_PRCLONING); 401 err = rtrequest(RTM_DELETE, (struct sockaddr *)rt_key(rt), 402 rt->rt_gateway, rt_mask(rt), rt->rt_flags, 0); 403 if (err) { 404 log(LOG_WARNING, "in_ifadownkill: error %d\n", err); 405 } 406 } 407 return 0; 408 } 409 410 int 411 in_ifadown(struct ifaddr *ifa, int delete) 412 { 413 struct in_ifadown_arg arg; 414 struct radix_node_head *rnh; 415 416 if (ifa->ifa_addr->sa_family != AF_INET) 417 return 1; 418 419 arg.rnh = rnh = rt_tables[AF_INET]; 420 arg.ifa = ifa; 421 arg.del = delete; 422 rnh->rnh_walktree(rnh, in_ifadownkill, &arg); 423 ifa->ifa_flags &= ~IFA_ROUTE; 424 return 0; 425 } 426