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