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