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d1dd20be6e
that covers updates to the contents. Note this is separate from holding a reference and/or locking the routing table itself. Other/related changes: o rtredirect loses the final parameter by which an rtentry reference may be returned; this was never used and added unwarranted complexity for locking. o minor style cleanups to routing code (e.g. ansi-fy function decls) o remove the logic to bump the refcnt on the parent of cloned routes, we assume the parent will remain as long as the clone; doing this avoids a circularity in locking during delete o convert some timeouts to MPSAFE callouts Notes: 1. rt_mtx in struct rtentry is guarded by #ifdef _KERNEL as user-level applications cannot/do-no know about mutex's. Doing this requires that the mutex be the last element in the structure. A better solution is to introduce an externalized version of struct rtentry but this is a major task because of the intertwining of rtentry and other data structures that are visible to user applications. 2. There are known LOR's that are expected to go away with forthcoming work to eliminate many held references. If not these will be resolved prior to release. 3. ATM changes are untested. Sponsored by: FreeBSD Foundation Obtained from: BSD/OS (partly)
433 lines
12 KiB
C
433 lines
12 KiB
C
/*
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* Copyright 1994, 1995 Massachusetts Institute of Technology
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*
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* Permission to use, copy, modify, and distribute this software and
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* its documentation for any purpose and without fee is hereby
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* granted, provided that both the above copyright notice and this
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* permission notice appear in all copies, that both the above
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* copyright notice and this permission notice appear in all
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* supporting documentation, and that the name of M.I.T. not be used
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* in advertising or publicity pertaining to distribution of the
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* software without specific, written prior permission. M.I.T. makes
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* no representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied
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* warranty.
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*
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* THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''. M.I.T. DISCLAIMS
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* ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
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* SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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/*
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* This code does two things necessary for the enhanced TCP metrics to
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* function in a useful manner:
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* 1) It marks all non-host routes as `cloning', thus ensuring that
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* every actual reference to such a route actually gets turned
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* into a reference to a host route to the specific destination
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* requested.
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* 2) When such routes lose all their references, it arranges for them
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* to be deleted in some random collection of circumstances, so that
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* a large quantity of stale routing data is not kept in kernel memory
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* indefinitely. See in_rtqtimo() below for the exact mechanism.
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/sysctl.h>
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#include <sys/socket.h>
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#include <sys/mbuf.h>
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#include <sys/syslog.h>
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#include <sys/callout.h>
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#include <net/if.h>
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#include <net/route.h>
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#include <netinet/in.h>
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#include <netinet/in_var.h>
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#include <netinet/ip_var.h>
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extern int in_inithead(void **head, int off);
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#define RTPRF_OURS RTF_PROTO3 /* set on routes we manage */
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/*
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* Do what we need to do when inserting a route.
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*/
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static struct radix_node *
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in_addroute(void *v_arg, void *n_arg, struct radix_node_head *head,
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struct radix_node *treenodes)
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{
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struct rtentry *rt = (struct rtentry *)treenodes;
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struct sockaddr_in *sin = (struct sockaddr_in *)rt_key(rt);
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struct radix_node *ret;
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/*
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* For IP, all unicast non-host routes are automatically cloning.
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*/
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if (IN_MULTICAST(ntohl(sin->sin_addr.s_addr)))
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rt->rt_flags |= RTF_MULTICAST;
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if (!(rt->rt_flags & (RTF_HOST | RTF_CLONING | RTF_MULTICAST)))
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rt->rt_flags |= RTF_PRCLONING;
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/*
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* A little bit of help for both IP output and input:
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* For host routes, we make sure that RTF_BROADCAST
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* is set for anything that looks like a broadcast address.
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* This way, we can avoid an expensive call to in_broadcast()
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* in ip_output() most of the time (because the route passed
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* to ip_output() is almost always a host route).
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*
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* We also do the same for local addresses, with the thought
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* that this might one day be used to speed up ip_input().
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*
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* We also mark routes to multicast addresses as such, because
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* it's easy to do and might be useful (but this is much more
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* dubious since it's so easy to inspect the address). (This
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* is done above.)
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*/
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if (rt->rt_flags & RTF_HOST) {
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if (in_broadcast(sin->sin_addr, rt->rt_ifp)) {
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rt->rt_flags |= RTF_BROADCAST;
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} else if (satosin(rt->rt_ifa->ifa_addr)->sin_addr.s_addr ==
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sin->sin_addr.s_addr) {
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rt->rt_flags |= RTF_LOCAL;
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}
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}
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if (!rt->rt_rmx.rmx_mtu && !(rt->rt_rmx.rmx_locks & RTV_MTU) &&
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rt->rt_ifp)
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rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu;
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ret = rn_addroute(v_arg, n_arg, head, treenodes);
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if (ret == NULL && rt->rt_flags & RTF_HOST) {
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struct rtentry *rt2;
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/*
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* We are trying to add a host route, but can't.
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* Find out if it is because of an
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* ARP entry and delete it if so.
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*/
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rt2 = rtalloc1((struct sockaddr *)sin, 0,
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RTF_CLONING | RTF_PRCLONING);
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if (rt2) {
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if (rt2->rt_flags & RTF_LLINFO &&
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rt2->rt_flags & RTF_HOST &&
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rt2->rt_gateway &&
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rt2->rt_gateway->sa_family == AF_LINK) {
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/* NB: must unlock to avoid recursion */
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RT_UNLOCK(rt2);
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rtrequest(RTM_DELETE,
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(struct sockaddr *)rt_key(rt2),
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rt2->rt_gateway, rt_mask(rt2),
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rt2->rt_flags, 0);
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ret = rn_addroute(v_arg, n_arg, head,
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treenodes);
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RT_LOCK(rt2);
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}
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RTFREE_LOCKED(rt2);
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}
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}
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/*
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* If the new route created successfully, and we are forwarding,
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* and there is a cached route, free it. Otherwise, we may end
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* up using the wrong route.
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*/
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if (ret != NULL && ipforwarding && ipforward_rt.ro_rt) {
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RTFREE(ipforward_rt.ro_rt);
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ipforward_rt.ro_rt = 0;
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}
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return ret;
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}
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/*
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* This code is the inverse of in_clsroute: on first reference, if we
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* were managing the route, stop doing so and set the expiration timer
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* back off again.
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*/
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static struct radix_node *
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in_matroute(void *v_arg, struct radix_node_head *head)
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{
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struct radix_node *rn = rn_match(v_arg, head);
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struct rtentry *rt = (struct rtentry *)rn;
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/*XXX locking? */
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if (rt && rt->rt_refcnt == 0) { /* this is first reference */
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if (rt->rt_flags & RTPRF_OURS) {
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rt->rt_flags &= ~RTPRF_OURS;
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rt->rt_rmx.rmx_expire = 0;
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}
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}
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return rn;
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}
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static int rtq_reallyold = 60*60; /* one hour is "really old" */
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SYSCTL_INT(_net_inet_ip, IPCTL_RTEXPIRE, rtexpire, CTLFLAG_RW,
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&rtq_reallyold, 0, "Default expiration time on dynamically learned routes");
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static int rtq_minreallyold = 10; /* never automatically crank down to less */
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SYSCTL_INT(_net_inet_ip, IPCTL_RTMINEXPIRE, rtminexpire, CTLFLAG_RW,
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&rtq_minreallyold, 0,
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"Minimum time to attempt to hold onto dynamically learned routes");
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static int rtq_toomany = 128; /* 128 cached routes is "too many" */
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SYSCTL_INT(_net_inet_ip, IPCTL_RTMAXCACHE, rtmaxcache, CTLFLAG_RW,
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&rtq_toomany, 0, "Upper limit on dynamically learned routes");
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/*
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* On last reference drop, mark the route as belong to us so that it can be
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* timed out.
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*/
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static void
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in_clsroute(struct radix_node *rn, struct radix_node_head *head)
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{
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struct rtentry *rt = (struct rtentry *)rn;
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RT_LOCK_ASSERT(rt);
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if (!(rt->rt_flags & RTF_UP))
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return; /* prophylactic measures */
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if ((rt->rt_flags & (RTF_LLINFO | RTF_HOST)) != RTF_HOST)
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return;
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if ((rt->rt_flags & (RTF_WASCLONED | RTPRF_OURS)) != RTF_WASCLONED)
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return;
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/*
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* If rtq_reallyold is 0, just delete the route without
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* waiting for a timeout cycle to kill it.
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*/
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if (rtq_reallyold != 0) {
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rt->rt_flags |= RTPRF_OURS;
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rt->rt_rmx.rmx_expire = time_second + rtq_reallyold;
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} else {
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/* NB: must unlock to avoid recursion */
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RT_UNLOCK(rt);
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rtrequest(RTM_DELETE,
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(struct sockaddr *)rt_key(rt),
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rt->rt_gateway, rt_mask(rt),
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rt->rt_flags, 0);
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RT_LOCK(rt);
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}
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}
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struct rtqk_arg {
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struct radix_node_head *rnh;
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int draining;
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int killed;
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int found;
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int updating;
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time_t nextstop;
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};
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/*
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* Get rid of old routes. When draining, this deletes everything, even when
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* the timeout is not expired yet. When updating, this makes sure that
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* nothing has a timeout longer than the current value of rtq_reallyold.
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*/
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static int
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in_rtqkill(struct radix_node *rn, void *rock)
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{
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struct rtqk_arg *ap = rock;
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struct rtentry *rt = (struct rtentry *)rn;
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int err;
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if (rt->rt_flags & RTPRF_OURS) {
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ap->found++;
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if (ap->draining || rt->rt_rmx.rmx_expire <= time_second) {
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if (rt->rt_refcnt > 0)
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panic("rtqkill route really not free");
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err = rtrequest(RTM_DELETE,
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(struct sockaddr *)rt_key(rt),
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rt->rt_gateway, rt_mask(rt),
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rt->rt_flags, 0);
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if (err) {
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log(LOG_WARNING, "in_rtqkill: error %d\n", err);
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} else {
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ap->killed++;
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}
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} else {
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if (ap->updating &&
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(rt->rt_rmx.rmx_expire - time_second >
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rtq_reallyold)) {
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rt->rt_rmx.rmx_expire =
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time_second + rtq_reallyold;
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}
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ap->nextstop = lmin(ap->nextstop,
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rt->rt_rmx.rmx_expire);
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}
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}
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return 0;
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}
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#define RTQ_TIMEOUT 60*10 /* run no less than once every ten minutes */
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static int rtq_timeout = RTQ_TIMEOUT;
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static struct callout rtq_timer;
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static void
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in_rtqtimo(void *rock)
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{
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struct radix_node_head *rnh = rock;
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struct rtqk_arg arg;
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struct timeval atv;
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static time_t last_adjusted_timeout = 0;
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arg.found = arg.killed = 0;
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arg.rnh = rnh;
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arg.nextstop = time_second + rtq_timeout;
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arg.draining = arg.updating = 0;
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RADIX_NODE_HEAD_LOCK(rnh);
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rnh->rnh_walktree(rnh, in_rtqkill, &arg);
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RADIX_NODE_HEAD_UNLOCK(rnh);
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/*
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* Attempt to be somewhat dynamic about this:
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* If there are ``too many'' routes sitting around taking up space,
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* then crank down the timeout, and see if we can't make some more
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* go away. However, we make sure that we will never adjust more
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* than once in rtq_timeout seconds, to keep from cranking down too
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* hard.
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*/
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if ((arg.found - arg.killed > rtq_toomany) &&
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(time_second - last_adjusted_timeout >= rtq_timeout) &&
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rtq_reallyold > rtq_minreallyold) {
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rtq_reallyold = 2 * rtq_reallyold / 3;
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if (rtq_reallyold < rtq_minreallyold) {
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rtq_reallyold = rtq_minreallyold;
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}
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last_adjusted_timeout = time_second;
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#ifdef DIAGNOSTIC
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log(LOG_DEBUG, "in_rtqtimo: adjusted rtq_reallyold to %d\n",
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rtq_reallyold);
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#endif
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arg.found = arg.killed = 0;
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arg.updating = 1;
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RADIX_NODE_HEAD_LOCK(rnh);
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rnh->rnh_walktree(rnh, in_rtqkill, &arg);
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RADIX_NODE_HEAD_UNLOCK(rnh);
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}
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atv.tv_usec = 0;
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atv.tv_sec = arg.nextstop - time_second;
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callout_reset(&rtq_timer, tvtohz(&atv), in_rtqtimo, rock);
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}
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void
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in_rtqdrain(void)
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{
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struct radix_node_head *rnh = rt_tables[AF_INET];
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struct rtqk_arg arg;
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arg.found = arg.killed = 0;
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arg.rnh = rnh;
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arg.nextstop = 0;
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arg.draining = 1;
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arg.updating = 0;
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RADIX_NODE_HEAD_LOCK(rnh);
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rnh->rnh_walktree(rnh, in_rtqkill, &arg);
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RADIX_NODE_HEAD_UNLOCK(rnh);
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}
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/*
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* Initialize our routing tree.
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*/
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int
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in_inithead(void **head, int off)
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{
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struct radix_node_head *rnh;
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if (!rn_inithead(head, off))
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return 0;
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if (head != (void **)&rt_tables[AF_INET]) /* BOGUS! */
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return 1; /* only do this for the real routing table */
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rnh = *head;
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rnh->rnh_addaddr = in_addroute;
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rnh->rnh_matchaddr = in_matroute;
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rnh->rnh_close = in_clsroute;
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callout_init(&rtq_timer, CALLOUT_MPSAFE);
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in_rtqtimo(rnh); /* kick off timeout first time */
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return 1;
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}
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/*
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* This zaps old routes when the interface goes down or interface
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* address is deleted. In the latter case, it deletes static routes
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* that point to this address. If we don't do this, we may end up
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* using the old address in the future. The ones we always want to
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* get rid of are things like ARP entries, since the user might down
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* the interface, walk over to a completely different network, and
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* plug back in.
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*/
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struct in_ifadown_arg {
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struct radix_node_head *rnh;
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struct ifaddr *ifa;
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int del;
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};
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static int
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in_ifadownkill(struct radix_node *rn, void *xap)
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{
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struct in_ifadown_arg *ap = xap;
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struct rtentry *rt = (struct rtentry *)rn;
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int err;
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if (rt->rt_ifa == ap->ifa &&
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(ap->del || !(rt->rt_flags & RTF_STATIC))) {
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/*
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* We need to disable the automatic prune that happens
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* in this case in rtrequest() because it will blow
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* away the pointers that rn_walktree() needs in order
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* continue our descent. We will end up deleting all
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* the routes that rtrequest() would have in any case,
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* so that behavior is not needed there.
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*/
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RT_LOCK(rt);
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rt->rt_flags &= ~(RTF_CLONING | RTF_PRCLONING);
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RT_UNLOCK(rt);
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err = rtrequest(RTM_DELETE, (struct sockaddr *)rt_key(rt),
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rt->rt_gateway, rt_mask(rt), rt->rt_flags, 0);
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if (err) {
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log(LOG_WARNING, "in_ifadownkill: error %d\n", err);
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}
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}
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return 0;
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}
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int
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in_ifadown(struct ifaddr *ifa, int delete)
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{
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struct in_ifadown_arg arg;
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struct radix_node_head *rnh;
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if (ifa->ifa_addr->sa_family != AF_INET)
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return 1;
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arg.rnh = rnh = rt_tables[AF_INET];
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arg.ifa = ifa;
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arg.del = delete;
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RADIX_NODE_HEAD_LOCK(rnh);
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rnh->rnh_walktree(rnh, in_ifadownkill, &arg);
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RADIX_NODE_HEAD_UNLOCK(rnh);
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ifa->ifa_flags &= ~IFA_ROUTE; /* XXXlocking? */
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return 0;
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}
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