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 * $FreeBSD$ 30 */ 31 32 /* 33 * This code does two things necessary for the enhanced TCP metrics to 34 * function in a useful manner: 35 * 1) It marks all non-host routes as `cloning', thus ensuring that 36 * every actual reference to such a route actually gets turned 37 * into a reference to a host route to the specific destination 38 * requested. 39 * 2) When such routes lose all their references, it arranges for them 40 * to be deleted in some random collection of circumstances, so that 41 * a large quantity of stale routing data is not kept in kernel memory 42 * indefinitely. See in_rtqtimo() below for the exact mechanism. 43 */ 44 45 #include <sys/param.h> 46 #include <sys/systm.h> 47 #include <sys/kernel.h> 48 #include <sys/sysctl.h> 49 #include <sys/socket.h> 50 #include <sys/mbuf.h> 51 #include <sys/syslog.h> 52 53 #include <net/if.h> 54 #include <net/route.h> 55 #include <netinet/in.h> 56 #include <netinet/in_var.h> 57 #include <netinet/ip_var.h> 58 59 extern int in_inithead(void **head, int off); 60 61 #define RTPRF_OURS RTF_PROTO3 /* set on routes we manage */ 62 63 /* 64 * Do what we need to do when inserting a route. 65 */ 66 static struct radix_node * 67 in_addroute(void *v_arg, void *n_arg, struct radix_node_head *head, 68 struct radix_node *treenodes) 69 { 70 struct rtentry *rt = (struct rtentry *)treenodes; 71 struct sockaddr_in *sin = (struct sockaddr_in *)rt_key(rt); 72 struct radix_node *ret; 73 74 /* 75 * For IP, all unicast non-host routes are automatically cloning. 76 */ 77 if (IN_MULTICAST(ntohl(sin->sin_addr.s_addr))) 78 rt->rt_flags |= RTF_MULTICAST; 79 80 if (!(rt->rt_flags & (RTF_HOST | RTF_CLONING | RTF_MULTICAST))) 81 rt->rt_flags |= RTF_PRCLONING; 82 83 /* 84 * A little bit of help for both IP output and input: 85 * For host routes, we make sure that RTF_BROADCAST 86 * is set for anything that looks like a broadcast address. 87 * This way, we can avoid an expensive call to in_broadcast() 88 * in ip_output() most of the time (because the route passed 89 * to ip_output() is almost always a host route). 90 * 91 * We also do the same for local addresses, with the thought 92 * that this might one day be used to speed up ip_input(). 93 * 94 * We also mark routes to multicast addresses as such, because 95 * it's easy to do and might be useful (but this is much more 96 * dubious since it's so easy to inspect the address). (This 97 * is done above.) 98 */ 99 if (rt->rt_flags & RTF_HOST) { 100 if (in_broadcast(sin->sin_addr, rt->rt_ifp)) { 101 rt->rt_flags |= RTF_BROADCAST; 102 } else if (satosin(rt->rt_ifa->ifa_addr)->sin_addr.s_addr == 103 sin->sin_addr.s_addr) { 104 rt->rt_flags |= RTF_LOCAL; 105 } 106 } 107 108 if (!rt->rt_rmx.rmx_mtu && !(rt->rt_rmx.rmx_locks & RTV_MTU) && 109 rt->rt_ifp) 110 rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu; 111 112 ret = rn_addroute(v_arg, n_arg, head, treenodes); 113 if (ret == NULL && rt->rt_flags & RTF_HOST) { 114 struct rtentry *rt2; 115 /* 116 * We are trying to add a host route, but can't. 117 * Find out if it is because of an 118 * ARP entry and delete it if so. 119 */ 120 rt2 = rtalloc1((struct sockaddr *)sin, 0, 121 RTF_CLONING | RTF_PRCLONING); 122 if (rt2) { 123 if (rt2->rt_flags & RTF_LLINFO && 124 rt2->rt_flags & RTF_HOST && 125 rt2->rt_gateway && 126 rt2->rt_gateway->sa_family == AF_LINK) { 127 rtrequest(RTM_DELETE, 128 (struct sockaddr *)rt_key(rt2), 129 rt2->rt_gateway, rt_mask(rt2), 130 rt2->rt_flags, 0); 131 ret = rn_addroute(v_arg, n_arg, head, 132 treenodes); 133 } 134 RTFREE(rt2); 135 } 136 } 137 138 /* 139 * If the new route created successfully, and we are forwarding, 140 * and there is a cached route, free it. Otherwise, we may end 141 * up using the wrong route. 142 */ 143 if (ret != NULL && ipforwarding && ipforward_rt.ro_rt) { 144 RTFREE(ipforward_rt.ro_rt); 145 ipforward_rt.ro_rt = 0; 146 } 147 148 return ret; 149 } 150 151 /* 152 * This code is the inverse of in_clsroute: on first reference, if we 153 * were managing the route, stop doing so and set the expiration timer 154 * back off again. 155 */ 156 static struct radix_node * 157 in_matroute(void *v_arg, struct radix_node_head *head) 158 { 159 struct radix_node *rn = rn_match(v_arg, head); 160 struct rtentry *rt = (struct rtentry *)rn; 161 162 if (rt && rt->rt_refcnt == 0) { /* this is first reference */ 163 if (rt->rt_flags & RTPRF_OURS) { 164 rt->rt_flags &= ~RTPRF_OURS; 165 rt->rt_rmx.rmx_expire = 0; 166 } 167 } 168 return rn; 169 } 170 171 static int rtq_reallyold = 60*60; /* one hour is "really old" */ 172 SYSCTL_INT(_net_inet_ip, IPCTL_RTEXPIRE, rtexpire, CTLFLAG_RW, 173 &rtq_reallyold, 0, "Default expiration time on dynamically learned routes"); 174 175 static int rtq_minreallyold = 10; /* never automatically crank down to less */ 176 SYSCTL_INT(_net_inet_ip, IPCTL_RTMINEXPIRE, rtminexpire, CTLFLAG_RW, 177 &rtq_minreallyold, 0, 178 "Minimum time to attempt to hold onto dynamically learned routes"); 179 180 static int rtq_toomany = 128; /* 128 cached routes is "too many" */ 181 SYSCTL_INT(_net_inet_ip, IPCTL_RTMAXCACHE, rtmaxcache, CTLFLAG_RW, 182 &rtq_toomany, 0, "Upper limit on dynamically learned routes"); 183 184 /* 185 * On last reference drop, mark the route as belong to us so that it can be 186 * timed out. 187 */ 188 static void 189 in_clsroute(struct radix_node *rn, struct radix_node_head *head) 190 { 191 struct rtentry *rt = (struct rtentry *)rn; 192 193 if (!(rt->rt_flags & RTF_UP)) 194 return; /* prophylactic measures */ 195 196 if ((rt->rt_flags & (RTF_LLINFO | RTF_HOST)) != RTF_HOST) 197 return; 198 199 if ((rt->rt_flags & (RTF_WASCLONED | RTPRF_OURS)) != RTF_WASCLONED) 200 return; 201 202 /* 203 * If rtq_reallyold is 0, just delete the route without 204 * waiting for a timeout cycle to kill it. 205 */ 206 if (rtq_reallyold != 0) { 207 rt->rt_flags |= RTPRF_OURS; 208 rt->rt_rmx.rmx_expire = time_second + rtq_reallyold; 209 } else { 210 rtrequest(RTM_DELETE, 211 (struct sockaddr *)rt_key(rt), 212 rt->rt_gateway, rt_mask(rt), 213 rt->rt_flags, 0); 214 } 215 } 216 217 struct rtqk_arg { 218 struct radix_node_head *rnh; 219 int draining; 220 int killed; 221 int found; 222 int updating; 223 time_t nextstop; 224 }; 225 226 /* 227 * Get rid of old routes. When draining, this deletes everything, even when 228 * the timeout is not expired yet. When updating, this makes sure that 229 * nothing has a timeout longer than the current value of rtq_reallyold. 230 */ 231 static int 232 in_rtqkill(struct radix_node *rn, void *rock) 233 { 234 struct rtqk_arg *ap = rock; 235 struct rtentry *rt = (struct rtentry *)rn; 236 int err; 237 238 if (rt->rt_flags & RTPRF_OURS) { 239 ap->found++; 240 241 if (ap->draining || rt->rt_rmx.rmx_expire <= time_second) { 242 if (rt->rt_refcnt > 0) 243 panic("rtqkill route really not free"); 244 245 err = rtrequest(RTM_DELETE, 246 (struct sockaddr *)rt_key(rt), 247 rt->rt_gateway, rt_mask(rt), 248 rt->rt_flags, 0); 249 if (err) { 250 log(LOG_WARNING, "in_rtqkill: error %d\n", err); 251 } else { 252 ap->killed++; 253 } 254 } else { 255 if (ap->updating && 256 (rt->rt_rmx.rmx_expire - time_second > 257 rtq_reallyold)) { 258 rt->rt_rmx.rmx_expire = 259 time_second + rtq_reallyold; 260 } 261 ap->nextstop = lmin(ap->nextstop, 262 rt->rt_rmx.rmx_expire); 263 } 264 } 265 266 return 0; 267 } 268 269 #define RTQ_TIMEOUT 60*10 /* run no less than once every ten minutes */ 270 static int rtq_timeout = RTQ_TIMEOUT; 271 272 static void 273 in_rtqtimo(void *rock) 274 { 275 struct radix_node_head *rnh = rock; 276 struct rtqk_arg arg; 277 struct timeval atv; 278 static time_t last_adjusted_timeout = 0; 279 int s; 280 281 arg.found = arg.killed = 0; 282 arg.rnh = rnh; 283 arg.nextstop = time_second + rtq_timeout; 284 arg.draining = arg.updating = 0; 285 s = splnet(); 286 RADIX_NODE_HEAD_LOCK(rnh); 287 rnh->rnh_walktree(rnh, in_rtqkill, &arg); 288 RADIX_NODE_HEAD_UNLOCK(rnh); 289 splx(s); 290 291 /* 292 * Attempt to be somewhat dynamic about this: 293 * If there are ``too many'' routes sitting around taking up space, 294 * then crank down the timeout, and see if we can't make some more 295 * go away. However, we make sure that we will never adjust more 296 * than once in rtq_timeout seconds, to keep from cranking down too 297 * hard. 298 */ 299 if ((arg.found - arg.killed > rtq_toomany) && 300 (time_second - last_adjusted_timeout >= rtq_timeout) && 301 rtq_reallyold > rtq_minreallyold) { 302 rtq_reallyold = 2 * rtq_reallyold / 3; 303 if (rtq_reallyold < rtq_minreallyold) { 304 rtq_reallyold = rtq_minreallyold; 305 } 306 307 last_adjusted_timeout = time_second; 308 #ifdef DIAGNOSTIC 309 log(LOG_DEBUG, "in_rtqtimo: adjusted rtq_reallyold to %d\n", 310 rtq_reallyold); 311 #endif 312 arg.found = arg.killed = 0; 313 arg.updating = 1; 314 s = splnet(); 315 RADIX_NODE_HEAD_LOCK(rnh); 316 rnh->rnh_walktree(rnh, in_rtqkill, &arg); 317 RADIX_NODE_HEAD_UNLOCK(rnh); 318 splx(s); 319 } 320 321 atv.tv_usec = 0; 322 atv.tv_sec = arg.nextstop - time_second; 323 timeout(in_rtqtimo, rock, tvtohz(&atv)); 324 } 325 326 void 327 in_rtqdrain(void) 328 { 329 struct radix_node_head *rnh = rt_tables[AF_INET]; 330 struct rtqk_arg arg; 331 int s; 332 arg.found = arg.killed = 0; 333 arg.rnh = rnh; 334 arg.nextstop = 0; 335 arg.draining = 1; 336 arg.updating = 0; 337 s = splnet(); 338 RADIX_NODE_HEAD_LOCK(rnh); 339 rnh->rnh_walktree(rnh, in_rtqkill, &arg); 340 RADIX_NODE_HEAD_UNLOCK(rnh); 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_matroute; 361 rnh->rnh_close = in_clsroute; 362 in_rtqtimo(rnh); /* kick off timeout first time */ 363 return 1; 364 } 365 366 /* 367 * This zaps old routes when the interface goes down or interface 368 * address is deleted. In the latter case, it deletes static routes 369 * that point to this address. If we don't do this, we may end up 370 * using the old address in the future. The ones we always want to 371 * get rid of are things like ARP entries, since the user might down 372 * the interface, walk over to a completely different network, and 373 * plug back in. 374 */ 375 struct in_ifadown_arg { 376 struct radix_node_head *rnh; 377 struct ifaddr *ifa; 378 int del; 379 }; 380 381 static int 382 in_ifadownkill(struct radix_node *rn, void *xap) 383 { 384 struct in_ifadown_arg *ap = xap; 385 struct rtentry *rt = (struct rtentry *)rn; 386 int err; 387 388 if (rt->rt_ifa == ap->ifa && 389 (ap->del || !(rt->rt_flags & RTF_STATIC))) { 390 /* 391 * We need to disable the automatic prune that happens 392 * in this case in rtrequest() because it will blow 393 * away the pointers that rn_walktree() needs in order 394 * continue our descent. We will end up deleting all 395 * the routes that rtrequest() would have in any case, 396 * so that behavior is not needed there. 397 */ 398 rt->rt_flags &= ~(RTF_CLONING | RTF_PRCLONING); 399 err = rtrequest(RTM_DELETE, (struct sockaddr *)rt_key(rt), 400 rt->rt_gateway, rt_mask(rt), rt->rt_flags, 0); 401 if (err) { 402 log(LOG_WARNING, "in_ifadownkill: error %d\n", err); 403 } 404 } 405 return 0; 406 } 407 408 int 409 in_ifadown(struct ifaddr *ifa, int delete) 410 { 411 struct in_ifadown_arg arg; 412 struct radix_node_head *rnh; 413 414 if (ifa->ifa_addr->sa_family != AF_INET) 415 return 1; 416 417 arg.rnh = rnh = rt_tables[AF_INET]; 418 arg.ifa = ifa; 419 arg.del = delete; 420 RADIX_NODE_HEAD_LOCK(rnh); 421 rnh->rnh_walktree(rnh, in_ifadownkill, &arg); 422 RADIX_NODE_HEAD_UNLOCK(rnh); 423 ifa->ifa_flags &= ~IFA_ROUTE; 424 return 0; 425 } 426