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8ea4cf79cb
freebsd/sys/netinet/if_ether.c
Julian Elischer 8b07e49a00 Add code to allow the system to handle multiple routing tables. 
This particular implementation is designed to be fully backwards compatible
and to be MFC-able to 7.x (and 6.x)

Currently the only protocol that can make use of the multiple tables is IPv4
Similar functionality exists in OpenBSD and Linux.

From my notes:

-----

  One thing where FreeBSD has been falling behind, and which by chance I
  have some time to work on is "policy based routing", which allows
  different
  packet streams to be routed by more than just the destination address.

  Constraints:
  ------------

  I want to make some form of this available in the 6.x tree
  (and by extension 7.x) , but FreeBSD in general needs it so I might as
  well do it in -current and back port the portions I need.

  One of the ways that this can be done is to have the ability to
  instantiate multiple kernel routing tables (which I will now
  refer to as "Forwarding Information Bases" or "FIBs" for political
  correctness reasons). Which FIB a particular packet uses to make
  the next hop decision can be decided by a number of mechanisms.
  The policies these mechanisms implement are the "Policies" referred
  to in "Policy based routing".

  One of the constraints I have if I try to back port this work to
  6.x is that it must be implemented as a EXTENSION to the existing
  ABIs in 6.x so that third party applications do not need to be
  recompiled in timespan of the branch.

  This first version will not have some of the bells and whistles that
  will come with later versions. It will, for example, be limited to 16
  tables in the first commit.
  Implementation method, Compatible version. (part 1)
  -------------------------------
  For this reason I have implemented a "sufficient subset" of a
  multiple routing table solution in Perforce, and back-ported it
  to 6.x. (also in Perforce though not  always caught up with what I
  have done in -current/P4). The subset allows a number of FIBs
  to be defined at compile time (8 is sufficient for my purposes in 6.x)
  and implements the changes needed to allow IPV4 to use them. I have not
  done the changes for ipv6 simply because I do not need it, and I do not
  have enough knowledge of ipv6 (e.g. neighbor discovery) needed to do it.

  Other protocol families are left untouched and should there be
  users with proprietary protocol families, they should continue to work
  and be oblivious to the existence of the extra FIBs.

  To understand how this is done, one must know that the current FIB
  code starts everything off with a single dimensional array of
  pointers to FIB head structures (One per protocol family), each of
  which in turn points to the trie of routes available to that family.

  The basic change in the ABI compatible version of the change is to
  extent that array to be a 2 dimensional array, so that
  instead of protocol family X looking at rt_tables[X] for the
  table it needs, it looks at rt_tables[Y][X] when for all
  protocol families except ipv4 Y is always 0.
  Code that is unaware of the change always just sees the first row
  of the table, which of course looks just like the one dimensional
  array that existed before.

  The entry points rtrequest(), rtalloc(), rtalloc1(), rtalloc_ign()
  are all maintained, but refer only to the first row of the array,
  so that existing callers in proprietary protocols can continue to
  do the "right thing".
  Some new entry points are added, for the exclusive use of ipv4 code
  called in_rtrequest(), in_rtalloc(), in_rtalloc1() and in_rtalloc_ign(),
  which have an extra argument which refers the code to the correct row.

  In addition, there are some new entry points (currently called
  rtalloc_fib() and friends) that check the Address family being
  looked up and call either rtalloc() (and friends) if the protocol
  is not IPv4 forcing the action to row 0 or to the appropriate row
  if it IS IPv4 (and that info is available). These are for calling
  from code that is not specific to any particular protocol. The way
  these are implemented would change in the non ABI preserving code
  to be added later.

  One feature of the first version of the code is that for ipv4,
  the interface routes show up automatically on all the FIBs, so
  that no matter what FIB you select you always have the basic
  direct attached hosts available to you. (rtinit() does this
  automatically).

  You CAN delete an interface route from one FIB should you want
  to but by default it's there. ARP information is also available
  in each FIB. It's assumed that the same machine would have the
  same MAC address, regardless of which FIB you are using to get
  to it.

  This brings us as to how the correct FIB is selected for an outgoing
  IPV4 packet.

  Firstly, all packets have a FIB associated with them. if nothing
  has been done to change it, it will be FIB 0. The FIB is changed
  in the following ways.

  Packets fall into one of a number of classes.

  1/ locally generated packets, coming from a socket/PCB.
     Such packets select a FIB from a number associated with the
     socket/PCB. This in turn is inherited from the process,
     but can be changed by a socket option. The process in turn
     inherits it on fork. I have written a utility call setfib
     that acts a bit like nice..

         setfib -3 ping target.example.com # will use fib 3 for ping.

     It is an obvious extension to make it a property of a jail
     but I have not done so. It can be achieved by combining the setfib and
     jail commands.

  2/ packets received on an interface for forwarding.
     By default these packets would use table 0,
     (or possibly a number settable in a sysctl(not yet)).
     but prior to routing the firewall can inspect them (see below).
     (possibly in the future you may be able to associate a FIB
     with packets received on an interface..  An ifconfig arg, but not yet.)

  3/ packets inspected by a packet classifier, which can arbitrarily
     associate a fib with it on a packet by packet basis.
     A fib assigned to a packet by a packet classifier
     (such as ipfw) would over-ride a fib associated by
     a more default source. (such as cases 1 or 2).

  4/ a tcp listen socket associated with a fib will generate
     accept sockets that are associated with that same fib.

  5/ Packets generated in response to some other packet (e.g. reset
     or icmp packets). These should use the FIB associated with the
     packet being reponded to.

  6/ Packets generated during encapsulation.
     gif, tun and other tunnel interfaces will encapsulate using the FIB
     that was in effect withthe proces that set up the tunnel.
     thus setfib 1 ifconfig gif0 [tunnel instructions]
     will set the fib for the tunnel to use to be fib 1.

  Routing messages would be associated with their
  process, and thus select one FIB or another.
  messages from the kernel would be associated with the fib they
  refer to and would only be received by a routing socket associated
  with that fib. (not yet implemented)

  In addition Netstat has been edited to be able to cope with the
  fact that the array is now 2 dimensional. (It looks in system
  memory using libkvm (!)). Old versions of netstat see only the first FIB.

  In addition two sysctls are added to give:
  a) the number of FIBs compiled in (active)
  b) the default FIB of the calling process.

  Early testing experience:
  -------------------------

  Basically our (IronPort's) appliance does this functionality already
  using ipfw fwd but that method has some drawbacks.

  For example,
  It can't fully simulate a routing table because it can't influence the
  socket's choice of local address when a connect() is done.

  Testing during the generating of these changes has been
  remarkably smooth so far. Multiple tables have co-existed
  with no notable side effects, and packets have been routes
  accordingly.

  ipfw has grown 2 new keywords:

  setfib N ip from anay to any
  count ip from any to any fib N

  In pf there seems to be a requirement to be able to give symbolic names to the
  fibs but I do not have that capacity. I am not sure if it is required.

  SCTP has interestingly enough built in support for this, called VRFs
  in Cisco parlance. it will be interesting to see how that handles it
  when it suddenly actually does something.

  Where to next:
  --------------------

  After committing the ABI compatible version and MFCing it, I'd
  like to proceed in a forward direction in -current. this will
  result in some roto-tilling in the routing code.

  Firstly: the current code's idea of having a separate tree per
  protocol family, all of the same format, and pointed to by the
  1 dimensional array is a bit silly. Especially when one considers that
  there is code that makes assumptions about every protocol having the
  same internal structures there. Some protocols don't WANT that
  sort of structure. (for example the whole idea of a netmask is foreign
  to appletalk). This needs to be made opaque to the external code.

  My suggested first change is to add routing method pointers to the
  'domain' structure, along with information pointing the data.
  instead of having an array of pointers to uniform structures,
  there would be an array pointing to the 'domain' structures
  for each protocol address domain (protocol family),
  and the methods this reached would be called. The methods would have
  an argument that gives FIB number, but the protocol would be free
  to ignore it.

  When the ABI can be changed it raises the possibilty of the
  addition of a fib entry into the "struct route". Currently,
  the structure contains the sockaddr of the desination, and the resulting
  fib entry. To make this work fully, one could add a fib number
  so that given an address and a fib, one can find the third element, the
  fib entry.

  Interaction with the ARP layer/ LL layer would need to be
  revisited as well. Qing Li has been working on this already.

  This work was sponsored by Ironport Systems/Cisco

Reviewed by:    several including rwatson, bz and mlair (parts each)
Obtained from:  Ironport systems/Cisco
2008-05-09 23:03:00 +00:00

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/*-
* Copyright (c) 1982, 1986, 1988, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)if_ether.c 8.1 (Berkeley) 6/10/93
*/
/*
* Ethernet address resolution protocol.
* TODO:
* add "inuse/lock" bit (or ref. count) along with valid bit
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_inet.h"
#include "opt_mac.h"
#include "opt_carp.h"
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/queue.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/socket.h>
#include <sys/syslog.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/route.h>
#include <net/netisr.h>
#include <net/if_llc.h>
#include <net/ethernet.h>
#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/if_ether.h>
#include <net/if_arc.h>
#include <net/iso88025.h>
#ifdef DEV_CARP
#include <netinet/ip_carp.h>
#endif
#include <security/mac/mac_framework.h>
#define SIN(s) ((struct sockaddr_in *)s)
#define SDL(s) ((struct sockaddr_dl *)s)
SYSCTL_DECL(_net_link_ether);
SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, "");
/* timer values */
static int arpt_keep = (20*60); /* once resolved, good for 20 more minutes */
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW,
&arpt_keep, 0, "ARP entry lifetime in seconds");
#define rt_expire rt_rmx.rmx_expire
struct llinfo_arp {
struct callout la_timer;
struct rtentry *la_rt;
struct mbuf *la_hold; /* last packet until resolved/timeout */
u_short la_preempt; /* countdown for pre-expiry arps */
u_short la_asked; /* # requests sent */
};
static struct ifqueue arpintrq;
static int arp_allocated;
static int arp_maxtries = 5;
static int useloopback = 1; /* use loopback interface for local traffic */
static int arp_proxyall = 0;
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
&arp_maxtries, 0, "ARP resolution attempts before returning error");
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW,
&useloopback, 0, "Use the loopback interface for local traffic");
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
&arp_proxyall, 0, "Enable proxy ARP for all suitable requests");
static void arp_init(void);
static void arp_rtrequest(int, struct rtentry *, struct rt_addrinfo *);
static void arprequest(struct ifnet *,
struct in_addr *, struct in_addr *, u_char *);
static void arpintr(struct mbuf *);
static void arptimer(void *);
static struct rtentry
*arplookup(u_long, int, int, int);
#ifdef INET
static void in_arpinput(struct mbuf *);
#endif
/*
* Timeout routine.
*/
static void
arptimer(void *arg)
{
struct rtentry *rt = (struct rtentry *)arg;
RT_LOCK_ASSERT(rt);
/*
* The lock is needed to close a theoretical race
* between spontaneous expiry and intentional removal.
* We still got an extra reference on rtentry, so can
* safely pass pointers to its contents.
*/
RT_UNLOCK(rt);
in_rtrequest(RTM_DELETE, rt_key(rt), NULL, rt_mask(rt), 0, NULL,
rt->rt_fibnum);
}
/*
* Parallel to llc_rtrequest.
*/
static void
arp_rtrequest(int req, struct rtentry *rt, struct rt_addrinfo *info)
{
struct sockaddr *gate;
struct llinfo_arp *la;
static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK};
struct in_ifaddr *ia;
struct ifaddr *ifa;
RT_LOCK_ASSERT(rt);
if (rt->rt_flags & RTF_GATEWAY)
return;
gate = rt->rt_gateway;
la = (struct llinfo_arp *)rt->rt_llinfo;
switch (req) {
case RTM_ADD:
/*
* XXX: If this is a manually added route to interface
* such as older version of routed or gated might provide,
* restore cloning bit.
*/
if ((rt->rt_flags & RTF_HOST) == 0 &&
rt_mask(rt) != NULL &&
SIN(rt_mask(rt))->sin_addr.s_addr != 0xffffffff)
rt->rt_flags |= RTF_CLONING;
if (rt->rt_flags & RTF_CLONING) {
/*
* Case 1: This route should come from a route to iface.
*/
rt_setgate(rt, rt_key(rt),
(struct sockaddr *)&null_sdl);
gate = rt->rt_gateway;
SDL(gate)->sdl_type = rt->rt_ifp->if_type;
SDL(gate)->sdl_index = rt->rt_ifp->if_index;
rt->rt_expire = time_uptime;
break;
}
/* Announce a new entry if requested. */
if (rt->rt_flags & RTF_ANNOUNCE)
arprequest(rt->rt_ifp,
&SIN(rt_key(rt))->sin_addr,
&SIN(rt_key(rt))->sin_addr,
(u_char *)LLADDR(SDL(gate)));
/*FALLTHROUGH*/
case RTM_RESOLVE:
if (gate->sa_family != AF_LINK ||
gate->sa_len < sizeof(null_sdl)) {
log(LOG_DEBUG, "%s: bad gateway %s%s\n", __func__,
inet_ntoa(SIN(rt_key(rt))->sin_addr),
(gate->sa_family != AF_LINK) ?
" (!AF_LINK)": "");
break;
}
SDL(gate)->sdl_type = rt->rt_ifp->if_type;
SDL(gate)->sdl_index = rt->rt_ifp->if_index;
if (la != 0)
break; /* This happens on a route change */
/*
* Case 2: This route may come from cloning, or a manual route
* add with a LL address.
*/
R_Zalloc(la, struct llinfo_arp *, sizeof(*la));
rt->rt_llinfo = (caddr_t)la;
if (la == 0) {
log(LOG_DEBUG, "%s: malloc failed\n", __func__);
break;
}
arp_allocated++;
/*
* We are storing a route entry outside of radix tree. So,
* it can be found and accessed by other means than radix
* lookup. The routing code assumes that any rtentry detached
* from radix can be destroyed safely. To prevent this, we
* add an additional reference.
*/
RT_ADDREF(rt);
la->la_rt = rt;
rt->rt_flags |= RTF_LLINFO;
callout_init_mtx(&la->la_timer, &rt->rt_mtx,
CALLOUT_RETURNUNLOCKED);
#ifdef INET
/*
* This keeps the multicast addresses from showing up
* in `arp -a' listings as unresolved. It's not actually
* functional. Then the same for broadcast.
*/
if (IN_MULTICAST(ntohl(SIN(rt_key(rt))->sin_addr.s_addr)) &&
rt->rt_ifp->if_type != IFT_ARCNET) {
ETHER_MAP_IP_MULTICAST(&SIN(rt_key(rt))->sin_addr,
LLADDR(SDL(gate)));
SDL(gate)->sdl_alen = 6;
rt->rt_expire = 0;
}
if (in_broadcast(SIN(rt_key(rt))->sin_addr, rt->rt_ifp)) {
memcpy(LLADDR(SDL(gate)), rt->rt_ifp->if_broadcastaddr,
rt->rt_ifp->if_addrlen);
SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen;
rt->rt_expire = 0;
}
#endif
TAILQ_FOREACH(ia, &in_ifaddrhead, ia_link) {
if (ia->ia_ifp == rt->rt_ifp &&
SIN(rt_key(rt))->sin_addr.s_addr ==
(IA_SIN(ia))->sin_addr.s_addr)
break;
}
if (ia) {
/*
* This test used to be
* if (loif.if_flags & IFF_UP)
* It allowed local traffic to be forced
* through the hardware by configuring the loopback down.
* However, it causes problems during network configuration
* for boards that can't receive packets they send.
* It is now necessary to clear "useloopback" and remove
* the route to force traffic out to the hardware.
*/
rt->rt_expire = 0;
bcopy(IF_LLADDR(rt->rt_ifp), LLADDR(SDL(gate)),
SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen);
if (useloopback) {
rt->rt_ifp = loif;
rt->rt_rmx.rmx_mtu = loif->if_mtu;
}
/*
* make sure to set rt->rt_ifa to the interface
* address we are using, otherwise we will have trouble
* with source address selection.
*/
ifa = &ia->ia_ifa;
if (ifa != rt->rt_ifa) {
IFAFREE(rt->rt_ifa);
IFAREF(ifa);
rt->rt_ifa = ifa;
}
}
break;
case RTM_DELETE:
if (la == NULL) /* XXX: at least CARP does this. */
break;
callout_stop(&la->la_timer);
rt->rt_llinfo = NULL;
rt->rt_flags &= ~RTF_LLINFO;
RT_REMREF(rt);
if (la->la_hold)
m_freem(la->la_hold);
Free((caddr_t)la);
}
}
/*
* Broadcast an ARP request. Caller specifies:
* - arp header source ip address
* - arp header target ip address
* - arp header source ethernet address
*/
static void
arprequest(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip,
u_char *enaddr)
{
struct mbuf *m;
struct arphdr *ah;
struct sockaddr sa;
if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL)
return;
m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) +
2*ifp->if_data.ifi_addrlen;
m->m_pkthdr.len = m->m_len;
MH_ALIGN(m, m->m_len);
ah = mtod(m, struct arphdr *);
bzero((caddr_t)ah, m->m_len);
#ifdef MAC
mac_netinet_arp_send(ifp, m);
#endif
ah->ar_pro = htons(ETHERTYPE_IP);
ah->ar_hln = ifp->if_addrlen; /* hardware address length */
ah->ar_pln = sizeof(struct in_addr); /* protocol address length */
ah->ar_op = htons(ARPOP_REQUEST);
bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln);
bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln);
bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln);
sa.sa_family = AF_ARP;
sa.sa_len = 2;
m->m_flags |= M_BCAST;
(*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0);
return;
}
/*
* Resolve an IP address into an ethernet address.
* On input:
* ifp is the interface we use
* rt0 is the route to the final destination (possibly useless)
* m is the mbuf. May be NULL if we don't have a packet.
* dst is the next hop,
* desten is where we want the address.
*
* On success, desten is filled in and the function returns 0;
* If the packet must be held pending resolution, we return EWOULDBLOCK
* On other errors, we return the corresponding error code.
* Note that m_freem() handles NULL.
*/
int
arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m,
struct sockaddr *dst, u_char *desten)
{
struct llinfo_arp *la = NULL;
struct rtentry *rt = NULL;
struct sockaddr_dl *sdl;
int error;
int fibnum = 0;
if (m) {
if (m->m_flags & M_BCAST) {
/* broadcast */
(void)memcpy(desten,
ifp->if_broadcastaddr, ifp->if_addrlen);
return (0);
}
if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {
/* multicast */
ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
return (0);
}
fibnum = M_GETFIB(m);
}
if (rt0 != NULL) {
/* Look for a cached arp (ll) entry. */
if (m == NULL)
fibnum = rt0->rt_fibnum;
error = in_rt_check(&rt, &rt0, dst, fibnum);
if (error) {
m_freem(m);
return error;
}
la = (struct llinfo_arp *)rt->rt_llinfo;
if (la == NULL)
RT_UNLOCK(rt);
}
if (la == NULL) {
/*
* We enter this block if rt0 was NULL,
* or if rt found by in_rt_check() didn't have llinfo.
* we should get a cloned route, which since it should
* come from the local interface should have a ll entry.
* if may be incoplete but that's ok.
* XXXMRT if we haven't found a fibnum is that OK?
*/
rt = arplookup(SIN(dst)->sin_addr.s_addr, 1, 0, fibnum);
if (rt == NULL) {
log(LOG_DEBUG,
"arpresolve: can't allocate route for %s\n",
inet_ntoa(SIN(dst)->sin_addr));
m_freem(m);
return (EINVAL); /* XXX */
}
la = (struct llinfo_arp *)rt->rt_llinfo;
if (la == NULL) {
RT_UNLOCK(rt);
log(LOG_DEBUG,
"arpresolve: can't allocate llinfo for %s\n",
inet_ntoa(SIN(dst)->sin_addr));
m_freem(m);
return (EINVAL); /* XXX */
}
}
sdl = SDL(rt->rt_gateway);
/*
* Check the address family and length is valid, the address
* is resolved; otherwise, try to resolve.
*/
if ((rt->rt_expire == 0 || rt->rt_expire > time_uptime) &&
sdl->sdl_family == AF_LINK && sdl->sdl_alen != 0) {
bcopy(LLADDR(sdl), desten, sdl->sdl_alen);
/*
* If entry has an expiry time and it is approaching,
* send an ARP request.
*/
if ((rt->rt_expire != 0) &&
(time_uptime + la->la_preempt > rt->rt_expire)) {
struct in_addr sin =
SIN(rt->rt_ifa->ifa_addr)->sin_addr;
la->la_preempt--;
RT_UNLOCK(rt);
arprequest(ifp, &sin, &SIN(dst)->sin_addr,
IF_LLADDR(ifp));
return (0);
}
RT_UNLOCK(rt);
return (0);
}
/*
* If ARP is disabled or static on this interface, stop.
* XXX
* Probably should not allocate empty llinfo struct if we are
* not going to be sending out an arp request.
*/
if (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) {
RT_UNLOCK(rt);
m_freem(m);
return (EINVAL);
}
/*
* There is an arptab entry, but no ethernet address
* response yet. Replace the held mbuf with this
* latest one.
*/
if (m) {
if (la->la_hold)
m_freem(la->la_hold);
la->la_hold = m;
}
KASSERT(rt->rt_expire > 0, ("sending ARP request for static entry"));
/*
* Return EWOULDBLOCK if we have tried less than arp_maxtries. It
* will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH
* if we have already sent arp_maxtries ARP requests. Retransmit the
* ARP request, but not faster than one request per second.
*/
if (la->la_asked < arp_maxtries)
error = EWOULDBLOCK; /* First request. */
else
error = (rt == rt0) ? EHOSTDOWN : EHOSTUNREACH;
if (la->la_asked == 0 || rt->rt_expire != time_uptime) {
struct in_addr sin =
SIN(rt->rt_ifa->ifa_addr)->sin_addr;
rt->rt_expire = time_uptime;
callout_reset(&la->la_timer, hz, arptimer, rt);
la->la_asked++;
RT_UNLOCK(rt);
arprequest(ifp, &sin, &SIN(dst)->sin_addr,
IF_LLADDR(ifp));
} else
RT_UNLOCK(rt);
return (error);
}
/*
* Common length and type checks are done here,
* then the protocol-specific routine is called.
*/
static void
arpintr(struct mbuf *m)
{
struct arphdr *ar;
if (m->m_len < sizeof(struct arphdr) &&
((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) {
log(LOG_ERR, "arp: runt packet -- m_pullup failed\n");
return;
}
ar = mtod(m, struct arphdr *);
if (ntohs(ar->ar_hrd) != ARPHRD_ETHER &&
ntohs(ar->ar_hrd) != ARPHRD_IEEE802 &&
ntohs(ar->ar_hrd) != ARPHRD_ARCNET &&
ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) {
log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n",
(unsigned char *)&ar->ar_hrd, "");
m_freem(m);
return;
}
if (m->m_len < arphdr_len(ar)) {
if ((m = m_pullup(m, arphdr_len(ar))) == NULL) {
log(LOG_ERR, "arp: runt packet\n");
m_freem(m);
return;
}
ar = mtod(m, struct arphdr *);
}
switch (ntohs(ar->ar_pro)) {
#ifdef INET
case ETHERTYPE_IP:
in_arpinput(m);
return;
#endif
}
m_freem(m);
}
#ifdef INET
/*
* ARP for Internet protocols on 10 Mb/s Ethernet.
* Algorithm is that given in RFC 826.
* In addition, a sanity check is performed on the sender
* protocol address, to catch impersonators.
* We no longer handle negotiations for use of trailer protocol:
* Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
* along with IP replies if we wanted trailers sent to us,
* and also sent them in response to IP replies.
* This allowed either end to announce the desire to receive
* trailer packets.
* We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
* but formerly didn't normally send requests.
*/
static int log_arp_wrong_iface = 1;
static int log_arp_movements = 1;
static int log_arp_permanent_modify = 1;
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW,
&log_arp_wrong_iface, 0,
"log arp packets arriving on the wrong interface");
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW,
&log_arp_movements, 0,
"log arp replies from MACs different than the one in the cache");
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW,
&log_arp_permanent_modify, 0,
"log arp replies from MACs different than the one in the permanent arp entry");
static void
in_arpinput(struct mbuf *m)
{
struct arphdr *ah;
struct ifnet *ifp = m->m_pkthdr.rcvif;
struct llinfo_arp *la;
struct rtentry *rt;
struct ifaddr *ifa;
struct in_ifaddr *ia;
struct sockaddr_dl *sdl;
struct sockaddr sa;
struct in_addr isaddr, itaddr, myaddr;
struct mbuf *hold;
u_int8_t *enaddr = NULL;
int op, rif_len;
int req_len;
int bridged = 0;
u_int fibnum;
u_int goodfib = 0;
int firstpass = 1;
#ifdef DEV_CARP
int carp_match = 0;
#endif
struct sockaddr_in sin;
sin.sin_len = sizeof(struct sockaddr_in);
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = 0;
if (ifp->if_bridge)
bridged = 1;
req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr));
if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) {
log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n");
return;
}
ah = mtod(m, struct arphdr *);
op = ntohs(ah->ar_op);
(void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr));
(void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr));
/*
* For a bridge, we want to check the address irrespective
* of the receive interface. (This will change slightly
* when we have clusters of interfaces).
* If the interface does not match, but the recieving interface
* is part of carp, we call carp_iamatch to see if this is a
* request for the virtual host ip.
* XXX: This is really ugly!
*/
LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) {
if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
(ia->ia_ifp == ifp)) &&
itaddr.s_addr == ia->ia_addr.sin_addr.s_addr)
goto match;
#ifdef DEV_CARP
if (ifp->if_carp != NULL &&
carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) &&
itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) {
carp_match = 1;
goto match;
}
#endif
}
LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
if (((bridged && ia->ia_ifp->if_bridge != NULL) ||
(ia->ia_ifp == ifp)) &&
isaddr.s_addr == ia->ia_addr.sin_addr.s_addr)
goto match;
/*
* No match, use the first inet address on the receive interface
* as a dummy address for the rest of the function.
*/
TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link)
if (ifa->ifa_addr->sa_family == AF_INET) {
ia = ifatoia(ifa);
goto match;
}
/*
* If bridging, fall back to using any inet address.
*/
if (!bridged || (ia = TAILQ_FIRST(&in_ifaddrhead)) == NULL)
goto drop;
match:
if (!enaddr)
enaddr = (u_int8_t *)IF_LLADDR(ifp);
myaddr = ia->ia_addr.sin_addr;
if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen))
goto drop; /* it's from me, ignore it. */
if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
log(LOG_ERR,
"arp: link address is broadcast for IP address %s!\n",
inet_ntoa(isaddr));
goto drop;
}
/*
* Warn if another host is using the same IP address, but only if the
* IP address isn't 0.0.0.0, which is used for DHCP only, in which
* case we suppress the warning to avoid false positive complaints of
* potential misconfiguration.
*/
if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) {
log(LOG_ERR,
"arp: %*D is using my IP address %s on %s!\n",
ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
inet_ntoa(isaddr), ifp->if_xname);
itaddr = myaddr;
goto reply;
}
if (ifp->if_flags & IFF_STATICARP)
goto reply;
/*
* We look for any FIBs that has this address to find
* the interface etc.
* For sanity checks that are FIB independent we abort the loop.
*/
for (fibnum = 0; fibnum < rt_numfibs; fibnum++) {
rt = arplookup(isaddr.s_addr,
itaddr.s_addr == myaddr.s_addr, 0, fibnum);
if (rt == NULL)
continue;
sdl = SDL(rt->rt_gateway);
/* Only call this once */
if (firstpass) {
sin.sin_addr.s_addr = isaddr.s_addr;
EVENTHANDLER_INVOKE(route_arp_update_event, rt,
ar_sha(ah), (struct sockaddr *)&sin);
}
la = (struct llinfo_arp *)rt->rt_llinfo;
if (la == NULL) {
RT_UNLOCK(rt);
continue;
}
if (firstpass) {
/* The following is not an error when doing bridging. */
if (!bridged && rt->rt_ifp != ifp
#ifdef DEV_CARP
&& (ifp->if_type != IFT_CARP || !carp_match)
#endif
) {
if (log_arp_wrong_iface)
log(LOG_ERR, "arp: %s is on %s "
"but got reply from %*D "
"on %s\n",
inet_ntoa(isaddr),
rt->rt_ifp->if_xname,
ifp->if_addrlen,
(u_char *)ar_sha(ah), ":",
ifp->if_xname);
RT_UNLOCK(rt);
break;
}
if (sdl->sdl_alen &&
bcmp(ar_sha(ah), LLADDR(sdl), sdl->sdl_alen)) {
if (rt->rt_expire) {
if (log_arp_movements)
log(LOG_INFO,
"arp: %s moved from %*D to %*D "
"on %s\n",
inet_ntoa(isaddr),
ifp->if_addrlen,
(u_char *)LLADDR(sdl), ":",
ifp->if_addrlen,
(u_char *)ar_sha(ah), ":",
ifp->if_xname);
} else {
RT_UNLOCK(rt);
if (log_arp_permanent_modify)
log(LOG_ERR,
"arp: %*D attempts to "
"modify permanent entry "
"for %s on %s\n",
ifp->if_addrlen,
(u_char *)ar_sha(ah), ":",
inet_ntoa(isaddr),
ifp->if_xname);
break;
}
}
/*
* sanity check for the address length.
* XXX this does not work for protocols
* with variable address length. -is
*/
if (sdl->sdl_alen &&
sdl->sdl_alen != ah->ar_hln) {
log(LOG_WARNING,
"arp from %*D: new addr len %d, was %d",
ifp->if_addrlen, (u_char *) ar_sha(ah),
":", ah->ar_hln, sdl->sdl_alen);
}
if (ifp->if_addrlen != ah->ar_hln) {
log(LOG_WARNING,
"arp from %*D: addr len: "
"new %d, i/f %d (ignored)",
ifp->if_addrlen, (u_char *) ar_sha(ah),
":", ah->ar_hln, ifp->if_addrlen);
RT_UNLOCK(rt);
break;
}
firstpass = 0;
goodfib = fibnum;
}
/* Copy in the information received. */
(void)memcpy(LLADDR(sdl), ar_sha(ah),
sdl->sdl_alen = ah->ar_hln);
/*
* If we receive an arp from a token-ring station over
* a token-ring nic then try to save the source routing info.
* XXXMRT Only minimal Token Ring support for MRT.
* Only do this on the first pass as if modifies the mbuf.
*/
if (ifp->if_type == IFT_ISO88025) {
struct iso88025_header *th = NULL;
struct iso88025_sockaddr_dl_data *trld;
/* force the fib loop to end after this pass */
fibnum = rt_numfibs - 1;
th = (struct iso88025_header *)m->m_pkthdr.header;
trld = SDL_ISO88025(sdl);
rif_len = TR_RCF_RIFLEN(th->rcf);
if ((th->iso88025_shost[0] & TR_RII) &&
(rif_len > 2)) {
trld->trld_rcf = th->rcf;
trld->trld_rcf ^= htons(TR_RCF_DIR);
memcpy(trld->trld_route, th->rd, rif_len - 2);
trld->trld_rcf &= ~htons(TR_RCF_BCST_MASK);
/*
* Set up source routing information for
* reply packet (XXX)
*/
m->m_data -= rif_len;
m->m_len += rif_len;
m->m_pkthdr.len += rif_len;
} else {
th->iso88025_shost[0] &= ~TR_RII;
trld->trld_rcf = 0;
}
m->m_data -= 8;
m->m_len += 8;
m->m_pkthdr.len += 8;
th->rcf = trld->trld_rcf;
}
if (rt->rt_expire) {
rt->rt_expire = time_uptime + arpt_keep;
callout_reset(&la->la_timer, hz * arpt_keep,
arptimer, rt);
}
la->la_asked = 0;
la->la_preempt = arp_maxtries;
hold = la->la_hold;
la->la_hold = NULL;
RT_UNLOCK(rt);
if (hold != NULL)
(*ifp->if_output)(ifp, hold, rt_key(rt), rt);
} /* end of FIB loop */
reply:
/*
* Decide if we have to respond to something.
*/
if (op != ARPOP_REQUEST)
goto drop;
if (itaddr.s_addr == myaddr.s_addr) {
/* Shortcut.. the receiving interface is the target. */
(void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
(void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
} else {
/* It's not asking for our address. But it still may
* be something we should answer.
*
* XXX MRT
* We assume that link level info is independent of
* the table used and so we use whichever we can and don't
* have a better option.
*/
/* Have we been asked to proxy for the target. */
rt = arplookup(itaddr.s_addr, 0, SIN_PROXY, goodfib);
if (rt == NULL) {
/* Nope, only intersted now if proxying everything. */
struct sockaddr_in sin;
if (!arp_proxyall)
goto drop;
bzero(&sin, sizeof sin);
sin.sin_family = AF_INET;
sin.sin_len = sizeof sin;
sin.sin_addr = itaddr;
/* XXX MRT use table 0 for arp reply */
rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
if (!rt)
goto drop;
/*
* Don't send proxies for nodes on the same interface
* as this one came out of, or we'll get into a fight
* over who claims what Ether address.
*/
if (rt->rt_ifp == ifp) {
rtfree(rt);
goto drop;
}
(void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
(void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
rtfree(rt);
/*
* Also check that the node which sent the ARP packet
* is on the the interface we expect it to be on. This
* avoids ARP chaos if an interface is connected to the
* wrong network.
*/
sin.sin_addr = isaddr;
/* XXX MRT use table 0 for arp checks */
rt = in_rtalloc1((struct sockaddr *)&sin, 0, 0UL, 0);
if (!rt)
goto drop;
if (rt->rt_ifp != ifp) {
log(LOG_INFO, "arp_proxy: ignoring request"
" from %s via %s, expecting %s\n",
inet_ntoa(isaddr), ifp->if_xname,
rt->rt_ifp->if_xname);
rtfree(rt);
goto drop;
}
rtfree(rt);
#ifdef DEBUG_PROXY
printf("arp: proxying for %s\n",
inet_ntoa(itaddr));
#endif
} else {
/*
* Return proxied ARP replies only on the interface
* or bridge cluster where this network resides.
* Otherwise we may conflict with the host we are
* proxying for.
*/
if (rt->rt_ifp != ifp &&
(rt->rt_ifp->if_bridge != ifp->if_bridge ||
ifp->if_bridge == NULL)) {
RT_UNLOCK(rt);
goto drop;
}
sdl = SDL(rt->rt_gateway);
(void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
(void)memcpy(ar_sha(ah), LLADDR(sdl), ah->ar_hln);
RT_UNLOCK(rt);
}
}
if (itaddr.s_addr == myaddr.s_addr &&
IN_LINKLOCAL(ntohl(itaddr.s_addr))) {
/* RFC 3927 link-local IPv4; always reply by broadcast. */
#ifdef DEBUG_LINKLOCAL
printf("arp: sending reply for link-local addr %s\n",
inet_ntoa(itaddr));
#endif
m->m_flags |= M_BCAST;
m->m_flags &= ~M_MCAST;
} else {
/* default behaviour; never reply by broadcast. */
m->m_flags &= ~(M_BCAST|M_MCAST);
}
(void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
(void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
ah->ar_op = htons(ARPOP_REPLY);
ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */
m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln);
m->m_pkthdr.len = m->m_len;
sa.sa_family = AF_ARP;
sa.sa_len = 2;
(*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0);
return;
drop:
m_freem(m);
}
#endif
/*
* Lookup or enter a new address in arptab.
*/
static struct rtentry *
arplookup(u_long addr, int create, int proxy, int fibnum)
{
struct rtentry *rt;
struct sockaddr_inarp sin;
const char *why = 0;
bzero(&sin, sizeof(sin));
sin.sin_len = sizeof(sin);
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = addr;
if (proxy)
sin.sin_other = SIN_PROXY;
rt = in_rtalloc1((struct sockaddr *)&sin, create, 0UL, fibnum);
if (rt == 0)
return (0);
if (rt->rt_flags & RTF_GATEWAY)
why = "host is not on local network";
else if ((rt->rt_flags & RTF_LLINFO) == 0)
why = "could not allocate llinfo";
else if (rt->rt_gateway->sa_family != AF_LINK)
why = "gateway route is not ours";
if (why) {
#define ISDYNCLONE(_rt) \
(((_rt)->rt_flags & (RTF_STATIC | RTF_WASCLONED)) == RTF_WASCLONED)
if (create)
log(LOG_DEBUG, "arplookup %s failed: %s\n",
inet_ntoa(sin.sin_addr), why);
/*
* If there are no references to this Layer 2 route,
* and it is a cloned route, and not static, and
* arplookup() is creating the route, then purge
* it from the routing table as it is probably bogus.
*/
if (rt->rt_refcnt == 1 && ISDYNCLONE(rt))
rtexpunge(rt);
RTFREE_LOCKED(rt);
return (0);
#undef ISDYNCLONE
} else {
RT_REMREF(rt);
return (rt);
}
}
void
arp_ifinit(struct ifnet *ifp, struct ifaddr *ifa)
{
if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY)
arprequest(ifp, &IA_SIN(ifa)->sin_addr,
&IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp));
ifa->ifa_rtrequest = arp_rtrequest;
ifa->ifa_flags |= RTF_CLONING;
}
void
arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr)
{
if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY)
arprequest(ifp, &IA_SIN(ifa)->sin_addr,
&IA_SIN(ifa)->sin_addr, enaddr);
ifa->ifa_rtrequest = arp_rtrequest;
ifa->ifa_flags |= RTF_CLONING;
}
static void
arp_init(void)
{
arpintrq.ifq_maxlen = 50;
mtx_init(&arpintrq.ifq_mtx, "arp_inq", NULL, MTX_DEF);
netisr_register(NETISR_ARP, arpintr, &arpintrq, NETISR_MPSAFE);
}
SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0);
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