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freebsd/sys/netinet/ip_output.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, 1990, 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.
*
* @(#)ip_output.c 8.3 (Berkeley) 1/21/94
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_ipfw.h"
#include "opt_ipsec.h"
#include "opt_mac.h"
#include "opt_mbuf_stress_test.h"
#include "opt_mpath.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sysctl.h>
#include <sys/ucred.h>
#include <net/if.h>
#include <net/netisr.h>
#include <net/pfil.h>
#include <net/route.h>
#ifdef RADIX_MPATH
#include <net/radix_mpath.h>
#endif
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet/ip_options.h>
#ifdef IPSEC
#include <netinet/ip_ipsec.h>
#include <netipsec/ipsec.h>
#endif /* IPSEC*/
#include <machine/in_cksum.h>
#include <security/mac/mac_framework.h>
#define print_ip(x, a, y) printf("%s %d.%d.%d.%d%s",\
x, (ntohl(a.s_addr)>>24)&0xFF,\
(ntohl(a.s_addr)>>16)&0xFF,\
(ntohl(a.s_addr)>>8)&0xFF,\
(ntohl(a.s_addr))&0xFF, y);
u_short ip_id;
#ifdef MBUF_STRESS_TEST
int mbuf_frag_size = 0;
SYSCTL_INT(_net_inet_ip, OID_AUTO, mbuf_frag_size, CTLFLAG_RW,
&mbuf_frag_size, 0, "Fragment outgoing mbufs to this size");
#endif
static void ip_mloopback
(struct ifnet *, struct mbuf *, struct sockaddr_in *, int);
extern struct protosw inetsw[];
/*
* IP output. The packet in mbuf chain m contains a skeletal IP
* header (with len, off, ttl, proto, tos, src, dst).
* The mbuf chain containing the packet will be freed.
* The mbuf opt, if present, will not be freed.
* In the IP forwarding case, the packet will arrive with options already
* inserted, so must have a NULL opt pointer.
*/
int
ip_output(struct mbuf *m, struct mbuf *opt, struct route *ro, int flags,
struct ip_moptions *imo, struct inpcb *inp)
{
struct ip *ip;
struct ifnet *ifp = NULL; /* keep compiler happy */
struct mbuf *m0;
int hlen = sizeof (struct ip);
int mtu;
int len, error = 0;
struct sockaddr_in *dst = NULL; /* keep compiler happy */
struct in_ifaddr *ia = NULL;
int isbroadcast, sw_csum;
struct route iproute;
struct in_addr odst;
#ifdef IPFIREWALL_FORWARD
struct m_tag *fwd_tag = NULL;
#endif
M_ASSERTPKTHDR(m);
if (ro == NULL) {
ro = &iproute;
bzero(ro, sizeof (*ro));
}
if (inp != NULL)
INP_LOCK_ASSERT(inp);
if (opt) {
len = 0;
m = ip_insertoptions(m, opt, &len);
if (len != 0)
hlen = len;
}
ip = mtod(m, struct ip *);
/*
* Fill in IP header. If we are not allowing fragmentation,
* then the ip_id field is meaningless, but we don't set it
* to zero. Doing so causes various problems when devices along
* the path (routers, load balancers, firewalls, etc.) illegally
* disable DF on our packet. Note that a 16-bit counter
* will wrap around in less than 10 seconds at 100 Mbit/s on a
* medium with MTU 1500. See Steven M. Bellovin, "A Technique
* for Counting NATted Hosts", Proc. IMW'02, available at
* <http://www.cs.columbia.edu/~smb/papers/fnat.pdf>.
*/
if ((flags & (IP_FORWARDING|IP_RAWOUTPUT)) == 0) {
ip->ip_v = IPVERSION;
ip->ip_hl = hlen >> 2;
ip->ip_id = ip_newid();
ipstat.ips_localout++;
} else {
hlen = ip->ip_hl << 2;
}
dst = (struct sockaddr_in *)&ro->ro_dst;
again:
/*
* If there is a cached route,
* check that it is to the same destination
* and is still up. If not, free it and try again.
* The address family should also be checked in case of sharing the
* cache with IPv6.
*/
if (ro->ro_rt && ((ro->ro_rt->rt_flags & RTF_UP) == 0 ||
dst->sin_family != AF_INET ||
dst->sin_addr.s_addr != ip->ip_dst.s_addr)) {
RTFREE(ro->ro_rt);
ro->ro_rt = (struct rtentry *)NULL;
}
#ifdef IPFIREWALL_FORWARD
if (ro->ro_rt == NULL && fwd_tag == NULL) {
#else
if (ro->ro_rt == NULL) {
#endif
bzero(dst, sizeof(*dst));
dst->sin_family = AF_INET;
dst->sin_len = sizeof(*dst);
dst->sin_addr = ip->ip_dst;
}
/*
* If routing to interface only, short circuit routing lookup.
* The use of an all-ones broadcast address implies this; an
* interface is specified by the broadcast address of an interface,
* or the destination address of a ptp interface.
*/
if (flags & IP_SENDONES) {
if ((ia = ifatoia(ifa_ifwithbroadaddr(sintosa(dst)))) == NULL &&
(ia = ifatoia(ifa_ifwithdstaddr(sintosa(dst)))) == NULL) {
ipstat.ips_noroute++;
error = ENETUNREACH;
goto bad;
}
ip->ip_dst.s_addr = INADDR_BROADCAST;
dst->sin_addr = ip->ip_dst;
ifp = ia->ia_ifp;
ip->ip_ttl = 1;
isbroadcast = 1;
} else if (flags & IP_ROUTETOIF) {
if ((ia = ifatoia(ifa_ifwithdstaddr(sintosa(dst)))) == NULL &&
(ia = ifatoia(ifa_ifwithnet(sintosa(dst)))) == NULL) {
ipstat.ips_noroute++;
error = ENETUNREACH;
goto bad;
}
ifp = ia->ia_ifp;
ip->ip_ttl = 1;
isbroadcast = in_broadcast(dst->sin_addr, ifp);
} else if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) &&
imo != NULL && imo->imo_multicast_ifp != NULL) {
/*
* Bypass the normal routing lookup for multicast
* packets if the interface is specified.
*/
ifp = imo->imo_multicast_ifp;
IFP_TO_IA(ifp, ia);
isbroadcast = 0; /* fool gcc */
} else {
/*
* We want to do any cloning requested by the link layer,
* as this is probably required in all cases for correct
* operation (as it is for ARP).
*/
if (ro->ro_rt == NULL)
#ifdef RADIX_MPATH
rtalloc_mpath_fib(ro,
ntohl(ip->ip_src.s_addr ^ ip->ip_dst.s_addr),
inp ? inp->inp_inc.inc_fibnum : M_GETFIB(m));
#else
in_rtalloc_ign(ro, 0,
inp ? inp->inp_inc.inc_fibnum : M_GETFIB(m));
#endif
if (ro->ro_rt == NULL) {
ipstat.ips_noroute++;
error = EHOSTUNREACH;
goto bad;
}
ia = ifatoia(ro->ro_rt->rt_ifa);
ifp = ro->ro_rt->rt_ifp;
ro->ro_rt->rt_rmx.rmx_pksent++;
if (ro->ro_rt->rt_flags & RTF_GATEWAY)
dst = (struct sockaddr_in *)ro->ro_rt->rt_gateway;
if (ro->ro_rt->rt_flags & RTF_HOST)
isbroadcast = (ro->ro_rt->rt_flags & RTF_BROADCAST);
else
isbroadcast = in_broadcast(dst->sin_addr, ifp);
}
/*
* Calculate MTU. If we have a route that is up, use that,
* otherwise use the interface's MTU.
*/
if (ro->ro_rt != NULL && (ro->ro_rt->rt_flags & (RTF_UP|RTF_HOST))) {
/*
* This case can happen if the user changed the MTU
* of an interface after enabling IP on it. Because
* most netifs don't keep track of routes pointing to
* them, there is no way for one to update all its
* routes when the MTU is changed.
*/
if (ro->ro_rt->rt_rmx.rmx_mtu > ifp->if_mtu)
ro->ro_rt->rt_rmx.rmx_mtu = ifp->if_mtu;
mtu = ro->ro_rt->rt_rmx.rmx_mtu;
} else {
mtu = ifp->if_mtu;
}
if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
struct in_multi *inm;
m->m_flags |= M_MCAST;
/*
* IP destination address is multicast. Make sure "dst"
* still points to the address in "ro". (It may have been
* changed to point to a gateway address, above.)
*/
dst = (struct sockaddr_in *)&ro->ro_dst;
/*
* See if the caller provided any multicast options
*/
if (imo != NULL) {
ip->ip_ttl = imo->imo_multicast_ttl;
if (imo->imo_multicast_vif != -1)
ip->ip_src.s_addr =
ip_mcast_src ?
ip_mcast_src(imo->imo_multicast_vif) :
INADDR_ANY;
} else
ip->ip_ttl = IP_DEFAULT_MULTICAST_TTL;
/*
* Confirm that the outgoing interface supports multicast.
*/
if ((imo == NULL) || (imo->imo_multicast_vif == -1)) {
if ((ifp->if_flags & IFF_MULTICAST) == 0) {
ipstat.ips_noroute++;
error = ENETUNREACH;
goto bad;
}
}
/*
* If source address not specified yet, use address
* of outgoing interface.
*/
if (ip->ip_src.s_addr == INADDR_ANY) {
/* Interface may have no addresses. */
if (ia != NULL)
ip->ip_src = IA_SIN(ia)->sin_addr;
}
IN_MULTI_LOCK();
IN_LOOKUP_MULTI(ip->ip_dst, ifp, inm);
if (inm != NULL &&
(imo == NULL || imo->imo_multicast_loop)) {
IN_MULTI_UNLOCK();
/*
* If we belong to the destination multicast group
* on the outgoing interface, and the caller did not
* forbid loopback, loop back a copy.
*/
ip_mloopback(ifp, m, dst, hlen);
}
else {
IN_MULTI_UNLOCK();
/*
* If we are acting as a multicast router, perform
* multicast forwarding as if the packet had just
* arrived on the interface to which we are about
* to send. The multicast forwarding function
* recursively calls this function, using the
* IP_FORWARDING flag to prevent infinite recursion.
*
* Multicasts that are looped back by ip_mloopback(),
* above, will be forwarded by the ip_input() routine,
* if necessary.
*/
if (ip_mrouter && (flags & IP_FORWARDING) == 0) {
/*
* If rsvp daemon is not running, do not
* set ip_moptions. This ensures that the packet
* is multicast and not just sent down one link
* as prescribed by rsvpd.
*/
if (!rsvp_on)
imo = NULL;
if (ip_mforward &&
ip_mforward(ip, ifp, m, imo) != 0) {
m_freem(m);
goto done;
}
}
}
/*
* Multicasts with a time-to-live of zero may be looped-
* back, above, but must not be transmitted on a network.
* Also, multicasts addressed to the loopback interface
* are not sent -- the above call to ip_mloopback() will
* loop back a copy if this host actually belongs to the
* destination group on the loopback interface.
*/
if (ip->ip_ttl == 0 || ifp->if_flags & IFF_LOOPBACK) {
m_freem(m);
goto done;
}
goto sendit;
}
/*
* If the source address is not specified yet, use the address
* of the outoing interface.
*/
if (ip->ip_src.s_addr == INADDR_ANY) {
/* Interface may have no addresses. */
if (ia != NULL) {
ip->ip_src = IA_SIN(ia)->sin_addr;
}
}
/*
* Verify that we have any chance at all of being able to queue the
* packet or packet fragments, unless ALTQ is enabled on the given
* interface in which case packetdrop should be done by queueing.
*/
#ifdef ALTQ
if ((!ALTQ_IS_ENABLED(&ifp->if_snd)) &&
((ifp->if_snd.ifq_len + ip->ip_len / mtu + 1) >=
ifp->if_snd.ifq_maxlen))
#else
if ((ifp->if_snd.ifq_len + ip->ip_len / mtu + 1) >=
ifp->if_snd.ifq_maxlen)
#endif /* ALTQ */
{
error = ENOBUFS;
ipstat.ips_odropped++;
ifp->if_snd.ifq_drops += (ip->ip_len / ifp->if_mtu + 1);
goto bad;
}
/*
* Look for broadcast address and
* verify user is allowed to send
* such a packet.
*/
if (isbroadcast) {
if ((ifp->if_flags & IFF_BROADCAST) == 0) {
error = EADDRNOTAVAIL;
goto bad;
}
if ((flags & IP_ALLOWBROADCAST) == 0) {
error = EACCES;
goto bad;
}
/* don't allow broadcast messages to be fragmented */
if (ip->ip_len > mtu) {
error = EMSGSIZE;
goto bad;
}
m->m_flags |= M_BCAST;
} else {
m->m_flags &= ~M_BCAST;
}
sendit:
#ifdef IPSEC
switch(ip_ipsec_output(&m, inp, &flags, &error, &ro, &iproute, &dst, &ia, &ifp)) {
case 1:
goto bad;
case -1:
goto done;
case 0:
default:
break; /* Continue with packet processing. */
}
/* Update variables that are affected by ipsec4_output(). */
ip = mtod(m, struct ip *);
hlen = ip->ip_hl << 2;
#endif /* IPSEC */
/* Jump over all PFIL processing if hooks are not active. */
if (!PFIL_HOOKED(&inet_pfil_hook))
goto passout;
/* Run through list of hooks for output packets. */
odst.s_addr = ip->ip_dst.s_addr;
error = pfil_run_hooks(&inet_pfil_hook, &m, ifp, PFIL_OUT, inp);
if (error != 0 || m == NULL)
goto done;
ip = mtod(m, struct ip *);
/* See if destination IP address was changed by packet filter. */
if (odst.s_addr != ip->ip_dst.s_addr) {
m->m_flags |= M_SKIP_FIREWALL;
/* If destination is now ourself drop to ip_input(). */
if (in_localip(ip->ip_dst)) {
m->m_flags |= M_FASTFWD_OURS;
if (m->m_pkthdr.rcvif == NULL)
m->m_pkthdr.rcvif = loif;
if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
m->m_pkthdr.csum_flags |=
CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
m->m_pkthdr.csum_data = 0xffff;
}
m->m_pkthdr.csum_flags |=
CSUM_IP_CHECKED | CSUM_IP_VALID;
error = netisr_queue(NETISR_IP, m);
goto done;
} else
goto again; /* Redo the routing table lookup. */
}
#ifdef IPFIREWALL_FORWARD
/* See if local, if yes, send it to netisr with IP_FASTFWD_OURS. */
if (m->m_flags & M_FASTFWD_OURS) {
if (m->m_pkthdr.rcvif == NULL)
m->m_pkthdr.rcvif = loif;
if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
m->m_pkthdr.csum_flags |=
CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
m->m_pkthdr.csum_data = 0xffff;
}
m->m_pkthdr.csum_flags |=
CSUM_IP_CHECKED | CSUM_IP_VALID;
error = netisr_queue(NETISR_IP, m);
goto done;
}
/* Or forward to some other address? */
fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL);
if (fwd_tag) {
dst = (struct sockaddr_in *)&ro->ro_dst;
bcopy((fwd_tag+1), dst, sizeof(struct sockaddr_in));
m->m_flags |= M_SKIP_FIREWALL;
m_tag_delete(m, fwd_tag);
goto again;
}
#endif /* IPFIREWALL_FORWARD */
passout:
/* 127/8 must not appear on wire - RFC1122. */
if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
(ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
if ((ifp->if_flags & IFF_LOOPBACK) == 0) {
ipstat.ips_badaddr++;
error = EADDRNOTAVAIL;
goto bad;
}
}
m->m_pkthdr.csum_flags |= CSUM_IP;
sw_csum = m->m_pkthdr.csum_flags & ~ifp->if_hwassist;
if (sw_csum & CSUM_DELAY_DATA) {
in_delayed_cksum(m);
sw_csum &= ~CSUM_DELAY_DATA;
}
m->m_pkthdr.csum_flags &= ifp->if_hwassist;
/*
* If small enough for interface, or the interface will take
* care of the fragmentation for us, we can just send directly.
*/
if (ip->ip_len <= mtu ||
(m->m_pkthdr.csum_flags & ifp->if_hwassist & CSUM_TSO) != 0 ||
((ip->ip_off & IP_DF) == 0 && (ifp->if_hwassist & CSUM_FRAGMENT))) {
ip->ip_len = htons(ip->ip_len);
ip->ip_off = htons(ip->ip_off);
ip->ip_sum = 0;
if (sw_csum & CSUM_DELAY_IP)
ip->ip_sum = in_cksum(m, hlen);
/*
* Record statistics for this interface address.
* With CSUM_TSO the byte/packet count will be slightly
* incorrect because we count the IP+TCP headers only
* once instead of for every generated packet.
*/
if (!(flags & IP_FORWARDING) && ia) {
if (m->m_pkthdr.csum_flags & CSUM_TSO)
ia->ia_ifa.if_opackets +=
m->m_pkthdr.len / m->m_pkthdr.tso_segsz;
else
ia->ia_ifa.if_opackets++;
ia->ia_ifa.if_obytes += m->m_pkthdr.len;
}
#ifdef MBUF_STRESS_TEST
if (mbuf_frag_size && m->m_pkthdr.len > mbuf_frag_size)
m = m_fragment(m, M_DONTWAIT, mbuf_frag_size);
#endif
/*
* Reset layer specific mbuf flags
* to avoid confusing lower layers.
*/
m->m_flags &= ~(M_PROTOFLAGS);
error = (*ifp->if_output)(ifp, m,
(struct sockaddr *)dst, ro->ro_rt);
goto done;
}
/* Balk when DF bit is set or the interface didn't support TSO. */
if ((ip->ip_off & IP_DF) || (m->m_pkthdr.csum_flags & CSUM_TSO)) {
error = EMSGSIZE;
ipstat.ips_cantfrag++;
goto bad;
}
/*
* Too large for interface; fragment if possible. If successful,
* on return, m will point to a list of packets to be sent.
*/
error = ip_fragment(ip, &m, mtu, ifp->if_hwassist, sw_csum);
if (error)
goto bad;
for (; m; m = m0) {
m0 = m->m_nextpkt;
m->m_nextpkt = 0;
if (error == 0) {
/* Record statistics for this interface address. */
if (ia != NULL) {
ia->ia_ifa.if_opackets++;
ia->ia_ifa.if_obytes += m->m_pkthdr.len;
}
/*
* Reset layer specific mbuf flags
* to avoid confusing upper layers.
*/
m->m_flags &= ~(M_PROTOFLAGS);
error = (*ifp->if_output)(ifp, m,
(struct sockaddr *)dst, ro->ro_rt);
} else
m_freem(m);
}
if (error == 0)
ipstat.ips_fragmented++;
done:
if (ro == &iproute && ro->ro_rt) {
RTFREE(ro->ro_rt);
}
return (error);
bad:
m_freem(m);
goto done;
}
/*
* Create a chain of fragments which fit the given mtu. m_frag points to the
* mbuf to be fragmented; on return it points to the chain with the fragments.
* Return 0 if no error. If error, m_frag may contain a partially built
* chain of fragments that should be freed by the caller.
*
* if_hwassist_flags is the hw offload capabilities (see if_data.ifi_hwassist)
* sw_csum contains the delayed checksums flags (e.g., CSUM_DELAY_IP).
*/
int
ip_fragment(struct ip *ip, struct mbuf **m_frag, int mtu,
u_long if_hwassist_flags, int sw_csum)
{
int error = 0;
int hlen = ip->ip_hl << 2;
int len = (mtu - hlen) & ~7; /* size of payload in each fragment */
int off;
struct mbuf *m0 = *m_frag; /* the original packet */
int firstlen;
struct mbuf **mnext;
int nfrags;
if (ip->ip_off & IP_DF) { /* Fragmentation not allowed */
ipstat.ips_cantfrag++;
return EMSGSIZE;
}
/*
* Must be able to put at least 8 bytes per fragment.
*/
if (len < 8)
return EMSGSIZE;
/*
* If the interface will not calculate checksums on
* fragmented packets, then do it here.
*/
if (m0->m_pkthdr.csum_flags & CSUM_DELAY_DATA &&
(if_hwassist_flags & CSUM_IP_FRAGS) == 0) {
in_delayed_cksum(m0);
m0->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
}
if (len > PAGE_SIZE) {
/*
* Fragment large datagrams such that each segment
* contains a multiple of PAGE_SIZE amount of data,
* plus headers. This enables a receiver to perform
* page-flipping zero-copy optimizations.
*
* XXX When does this help given that sender and receiver
* could have different page sizes, and also mtu could
* be less than the receiver's page size ?
*/
int newlen;
struct mbuf *m;
for (m = m0, off = 0; m && (off+m->m_len) <= mtu; m = m->m_next)
off += m->m_len;
/*
* firstlen (off - hlen) must be aligned on an
* 8-byte boundary
*/
if (off < hlen)
goto smart_frag_failure;
off = ((off - hlen) & ~7) + hlen;
newlen = (~PAGE_MASK) & mtu;
if ((newlen + sizeof (struct ip)) > mtu) {
/* we failed, go back the default */
smart_frag_failure:
newlen = len;
off = hlen + len;
}
len = newlen;
} else {
off = hlen + len;
}
firstlen = off - hlen;
mnext = &m0->m_nextpkt; /* pointer to next packet */
/*
* Loop through length of segment after first fragment,
* make new header and copy data of each part and link onto chain.
* Here, m0 is the original packet, m is the fragment being created.
* The fragments are linked off the m_nextpkt of the original
* packet, which after processing serves as the first fragment.
*/
for (nfrags = 1; off < ip->ip_len; off += len, nfrags++) {
struct ip *mhip; /* ip header on the fragment */
struct mbuf *m;
int mhlen = sizeof (struct ip);
MGETHDR(m, M_DONTWAIT, MT_DATA);
if (m == NULL) {
error = ENOBUFS;
ipstat.ips_odropped++;
goto done;
}
m->m_flags |= (m0->m_flags & M_MCAST) | M_FRAG;
/*
* In the first mbuf, leave room for the link header, then
* copy the original IP header including options. The payload
* goes into an additional mbuf chain returned by m_copy().
*/
m->m_data += max_linkhdr;
mhip = mtod(m, struct ip *);
*mhip = *ip;
if (hlen > sizeof (struct ip)) {
mhlen = ip_optcopy(ip, mhip) + sizeof (struct ip);
mhip->ip_v = IPVERSION;
mhip->ip_hl = mhlen >> 2;
}
m->m_len = mhlen;
/* XXX do we need to add ip->ip_off below ? */
mhip->ip_off = ((off - hlen) >> 3) + ip->ip_off;
if (off + len >= ip->ip_len) { /* last fragment */
len = ip->ip_len - off;
m->m_flags |= M_LASTFRAG;
} else
mhip->ip_off |= IP_MF;
mhip->ip_len = htons((u_short)(len + mhlen));
m->m_next = m_copy(m0, off, len);
if (m->m_next == NULL) { /* copy failed */
m_free(m);
error = ENOBUFS; /* ??? */
ipstat.ips_odropped++;
goto done;
}
m->m_pkthdr.len = mhlen + len;
m->m_pkthdr.rcvif = NULL;
#ifdef MAC
mac_netinet_fragment(m0, m);
#endif
m->m_pkthdr.csum_flags = m0->m_pkthdr.csum_flags;
mhip->ip_off = htons(mhip->ip_off);
mhip->ip_sum = 0;
if (sw_csum & CSUM_DELAY_IP)
mhip->ip_sum = in_cksum(m, mhlen);
*mnext = m;
mnext = &m->m_nextpkt;
}
ipstat.ips_ofragments += nfrags;
/* set first marker for fragment chain */
m0->m_flags |= M_FIRSTFRAG | M_FRAG;
m0->m_pkthdr.csum_data = nfrags;
/*
* Update first fragment by trimming what's been copied out
* and updating header.
*/
m_adj(m0, hlen + firstlen - ip->ip_len);
m0->m_pkthdr.len = hlen + firstlen;
ip->ip_len = htons((u_short)m0->m_pkthdr.len);
ip->ip_off |= IP_MF;
ip->ip_off = htons(ip->ip_off);
ip->ip_sum = 0;
if (sw_csum & CSUM_DELAY_IP)
ip->ip_sum = in_cksum(m0, hlen);
done:
*m_frag = m0;
return error;
}
void
in_delayed_cksum(struct mbuf *m)
{
struct ip *ip;
u_short csum, offset;
ip = mtod(m, struct ip *);
offset = ip->ip_hl << 2 ;
csum = in_cksum_skip(m, ip->ip_len, offset);
if (m->m_pkthdr.csum_flags & CSUM_UDP && csum == 0)
csum = 0xffff;
offset += m->m_pkthdr.csum_data; /* checksum offset */
if (offset + sizeof(u_short) > m->m_len) {
printf("delayed m_pullup, m->len: %d off: %d p: %d\n",
m->m_len, offset, ip->ip_p);
/*
* XXX
* this shouldn't happen, but if it does, the
* correct behavior may be to insert the checksum
* in the appropriate next mbuf in the chain.
*/
return;
}
*(u_short *)(m->m_data + offset) = csum;
}
/*
* IP socket option processing.
*/
int
ip_ctloutput(struct socket *so, struct sockopt *sopt)
{
struct inpcb *inp = sotoinpcb(so);
int error, optval;
error = optval = 0;
if (sopt->sopt_level != IPPROTO_IP) {
return (EINVAL);
}
switch (sopt->sopt_dir) {
case SOPT_SET:
switch (sopt->sopt_name) {
case IP_OPTIONS:
#ifdef notyet
case IP_RETOPTS:
#endif
{
struct mbuf *m;
if (sopt->sopt_valsize > MLEN) {
error = EMSGSIZE;
break;
}
MGET(m, sopt->sopt_td ? M_WAIT : M_DONTWAIT, MT_DATA);
if (m == NULL) {
error = ENOBUFS;
break;
}
m->m_len = sopt->sopt_valsize;
error = sooptcopyin(sopt, mtod(m, char *), m->m_len,
m->m_len);
if (error) {
m_free(m);
break;
}
INP_WLOCK(inp);
error = ip_pcbopts(inp, sopt->sopt_name, m);
INP_WUNLOCK(inp);
return (error);
}
case IP_TOS:
case IP_TTL:
case IP_MINTTL:
case IP_RECVOPTS:
case IP_RECVRETOPTS:
case IP_RECVDSTADDR:
case IP_RECVTTL:
case IP_RECVIF:
case IP_FAITH:
case IP_ONESBCAST:
case IP_DONTFRAG:
error = sooptcopyin(sopt, &optval, sizeof optval,
sizeof optval);
if (error)
break;
switch (sopt->sopt_name) {
case IP_TOS:
inp->inp_ip_tos = optval;
break;
case IP_TTL:
inp->inp_ip_ttl = optval;
break;
case IP_MINTTL:
if (optval > 0 && optval <= MAXTTL)
inp->inp_ip_minttl = optval;
else
error = EINVAL;
break;
#define OPTSET(bit) do { \
INP_WLOCK(inp); \
if (optval) \
inp->inp_flags |= bit; \
else \
inp->inp_flags &= ~bit; \
INP_WUNLOCK(inp); \
} while (0)
case IP_RECVOPTS:
OPTSET(INP_RECVOPTS);
break;
case IP_RECVRETOPTS:
OPTSET(INP_RECVRETOPTS);
break;
case IP_RECVDSTADDR:
OPTSET(INP_RECVDSTADDR);
break;
case IP_RECVTTL:
OPTSET(INP_RECVTTL);
break;
case IP_RECVIF:
OPTSET(INP_RECVIF);
break;
case IP_FAITH:
OPTSET(INP_FAITH);
break;
case IP_ONESBCAST:
OPTSET(INP_ONESBCAST);
break;
case IP_DONTFRAG:
OPTSET(INP_DONTFRAG);
break;
}
break;
#undef OPTSET
/*
* Multicast socket options are processed by the in_mcast
* module.
*/
case IP_MULTICAST_IF:
case IP_MULTICAST_VIF:
case IP_MULTICAST_TTL:
case IP_MULTICAST_LOOP:
case IP_ADD_MEMBERSHIP:
case IP_DROP_MEMBERSHIP:
case IP_ADD_SOURCE_MEMBERSHIP:
case IP_DROP_SOURCE_MEMBERSHIP:
case IP_BLOCK_SOURCE:
case IP_UNBLOCK_SOURCE:
case IP_MSFILTER:
case MCAST_JOIN_GROUP:
case MCAST_LEAVE_GROUP:
case MCAST_JOIN_SOURCE_GROUP:
case MCAST_LEAVE_SOURCE_GROUP:
case MCAST_BLOCK_SOURCE:
case MCAST_UNBLOCK_SOURCE:
error = inp_setmoptions(inp, sopt);
break;
case IP_PORTRANGE:
error = sooptcopyin(sopt, &optval, sizeof optval,
sizeof optval);
if (error)
break;
INP_WLOCK(inp);
switch (optval) {
case IP_PORTRANGE_DEFAULT:
inp->inp_flags &= ~(INP_LOWPORT);
inp->inp_flags &= ~(INP_HIGHPORT);
break;
case IP_PORTRANGE_HIGH:
inp->inp_flags &= ~(INP_LOWPORT);
inp->inp_flags |= INP_HIGHPORT;
break;
case IP_PORTRANGE_LOW:
inp->inp_flags &= ~(INP_HIGHPORT);
inp->inp_flags |= INP_LOWPORT;
break;
default:
error = EINVAL;
break;
}
INP_WUNLOCK(inp);
break;
#ifdef IPSEC
case IP_IPSEC_POLICY:
{
caddr_t req;
struct mbuf *m;
if ((error = soopt_getm(sopt, &m)) != 0) /* XXX */
break;
if ((error = soopt_mcopyin(sopt, m)) != 0) /* XXX */
break;
req = mtod(m, caddr_t);
error = ipsec4_set_policy(inp, sopt->sopt_name, req,
m->m_len, (sopt->sopt_td != NULL) ?
sopt->sopt_td->td_ucred : NULL);
m_freem(m);
break;
}
#endif /* IPSEC */
default:
error = ENOPROTOOPT;
break;
}
break;
case SOPT_GET:
switch (sopt->sopt_name) {
case IP_OPTIONS:
case IP_RETOPTS:
if (inp->inp_options)
error = sooptcopyout(sopt,
mtod(inp->inp_options,
char *),
inp->inp_options->m_len);
else
sopt->sopt_valsize = 0;
break;
case IP_TOS:
case IP_TTL:
case IP_MINTTL:
case IP_RECVOPTS:
case IP_RECVRETOPTS:
case IP_RECVDSTADDR:
case IP_RECVTTL:
case IP_RECVIF:
case IP_PORTRANGE:
case IP_FAITH:
case IP_ONESBCAST:
case IP_DONTFRAG:
switch (sopt->sopt_name) {
case IP_TOS:
optval = inp->inp_ip_tos;
break;
case IP_TTL:
optval = inp->inp_ip_ttl;
break;
case IP_MINTTL:
optval = inp->inp_ip_minttl;
break;
#define OPTBIT(bit) (inp->inp_flags & bit ? 1 : 0)
case IP_RECVOPTS:
optval = OPTBIT(INP_RECVOPTS);
break;
case IP_RECVRETOPTS:
optval = OPTBIT(INP_RECVRETOPTS);
break;
case IP_RECVDSTADDR:
optval = OPTBIT(INP_RECVDSTADDR);
break;
case IP_RECVTTL:
optval = OPTBIT(INP_RECVTTL);
break;
case IP_RECVIF:
optval = OPTBIT(INP_RECVIF);
break;
case IP_PORTRANGE:
if (inp->inp_flags & INP_HIGHPORT)
optval = IP_PORTRANGE_HIGH;
else if (inp->inp_flags & INP_LOWPORT)
optval = IP_PORTRANGE_LOW;
else
optval = 0;
break;
case IP_FAITH:
optval = OPTBIT(INP_FAITH);
break;
case IP_ONESBCAST:
optval = OPTBIT(INP_ONESBCAST);
break;
case IP_DONTFRAG:
optval = OPTBIT(INP_DONTFRAG);
break;
}
error = sooptcopyout(sopt, &optval, sizeof optval);
break;
/*
* Multicast socket options are processed by the in_mcast
* module.
*/
case IP_MULTICAST_IF:
case IP_MULTICAST_VIF:
case IP_MULTICAST_TTL:
case IP_MULTICAST_LOOP:
case IP_MSFILTER:
error = inp_getmoptions(inp, sopt);
break;
#ifdef IPSEC
case IP_IPSEC_POLICY:
{
struct mbuf *m = NULL;
caddr_t req = NULL;
size_t len = 0;
if (m != 0) {
req = mtod(m, caddr_t);
len = m->m_len;
}
error = ipsec4_get_policy(sotoinpcb(so), req, len, &m);
if (error == 0)
error = soopt_mcopyout(sopt, m); /* XXX */
if (error == 0)
m_freem(m);
break;
}
#endif /* IPSEC */
default:
error = ENOPROTOOPT;
break;
}
break;
}
return (error);
}
/*
* Routine called from ip_output() to loop back a copy of an IP multicast
* packet to the input queue of a specified interface. Note that this
* calls the output routine of the loopback "driver", but with an interface
* pointer that might NOT be a loopback interface -- evil, but easier than
* replicating that code here.
*/
static void
ip_mloopback(struct ifnet *ifp, struct mbuf *m, struct sockaddr_in *dst,
int hlen)
{
register struct ip *ip;
struct mbuf *copym;
copym = m_copy(m, 0, M_COPYALL);
if (copym != NULL && (copym->m_flags & M_EXT || copym->m_len < hlen))
copym = m_pullup(copym, hlen);
if (copym != NULL) {
/* If needed, compute the checksum and mark it as valid. */
if (copym->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
in_delayed_cksum(copym);
copym->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
copym->m_pkthdr.csum_flags |=
CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
copym->m_pkthdr.csum_data = 0xffff;
}
/*
* We don't bother to fragment if the IP length is greater
* than the interface's MTU. Can this possibly matter?
*/
ip = mtod(copym, struct ip *);
ip->ip_len = htons(ip->ip_len);
ip->ip_off = htons(ip->ip_off);
ip->ip_sum = 0;
ip->ip_sum = in_cksum(copym, hlen);
/*
* NB:
* It's not clear whether there are any lingering
* reentrancy problems in other areas which might
* be exposed by using ip_input directly (in
* particular, everything which modifies the packet
* in-place). Yet another option is using the
* protosw directly to deliver the looped back
* packet. For the moment, we'll err on the side
* of safety by using if_simloop().
*/
#if 1 /* XXX */
if (dst->sin_family != AF_INET) {
printf("ip_mloopback: bad address family %d\n",
dst->sin_family);
dst->sin_family = AF_INET;
}
#endif
#ifdef notdef
copym->m_pkthdr.rcvif = ifp;
ip_input(copym);
#else
if_simloop(ifp, copym, dst->sin_family, 0);
#endif
}
}
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