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freebsd-dev/sys/netinet/ip_output.c
Bjoern A. Zeeb c744cde428 Try to catch a possible divide-by-zero as early as possible if "mtu" is 0 
(also test for negative MTUs if checking it anyway).
An MTU of 0 is arguably a bug elsewhere, but this at least gives us some
more debugging hints.

Sponsored by:	ISPsystem (Early 2010)
MFC after:	1 week
2010-12-31 21:47:11 +00:00

1280 lines
32 KiB
C
Raw Blame History

/*-
* 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_route.h"
#include "opt_mbuf_stress_test.h"
#include "opt_mpath.h"
#include "opt_sctp.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/if_llatbl.h>
#include <net/netisr.h>
#include <net/pfil.h>
#include <net/route.h>
#include <net/flowtable.h>
#ifdef RADIX_MPATH
#include <net/radix_mpath.h>
#endif
#include <net/vnet.h>
#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 SCTP
#include <netinet/sctp.h>
#include <netinet/sctp_crc32.h>
#endif
#ifdef IPSEC
#include <netinet/ip_ipsec.h>
#include <netipsec/ipsec.h>
#endif /* IPSEC*/
#include <machine/in_cksum.h>
#include <security/mac/mac_framework.h>
VNET_DEFINE(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 int in_mcast_loop;
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).
* ip_len and ip_off are in host format.
* 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 n; /* scratchpad */
int error = 0;
int nortfree = 0;
struct sockaddr_in *dst;
struct in_ifaddr *ia = NULL;
int isbroadcast, sw_csum;
struct route iproute;
struct rtentry *rte; /* cache for ro->ro_rt */
struct in_addr odst;
#ifdef IPFIREWALL_FORWARD
struct m_tag *fwd_tag = NULL;
#endif
#ifdef IPSEC
int no_route_but_check_spd = 0;
#endif
M_ASSERTPKTHDR(m);
if (inp != NULL) {
INP_LOCK_ASSERT(inp);
M_SETFIB(m, inp->inp_inc.inc_fibnum);
if (inp->inp_flags & (INP_HW_FLOWID|INP_SW_FLOWID)) {
m->m_pkthdr.flowid = inp->inp_flowid;
m->m_flags |= M_FLOWID;
}
}
if (ro == NULL) {
ro = &iproute;
bzero(ro, sizeof (*ro));
#ifdef FLOWTABLE
{
struct flentry *fle;
/*
* The flow table returns route entries valid for up to 30
* seconds; we rely on the remainder of ip_output() taking no
* longer than that long for the stability of ro_rt. The
* flow ID assignment must have happened before this point.
*/
if ((fle = flowtable_lookup_mbuf(V_ip_ft, m, AF_INET)) != NULL) {
flow_to_route(fle, ro);
nortfree = 1;
}
}
#endif
}
if (opt) {
int len = 0;
m = ip_insertoptions(m, opt, &len);
if (len != 0)
hlen = len; /* ip->ip_hl is updated above */
}
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_INC(ips_localout);
} else {
/* Header already set, fetch hlen from there */
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.
*/
rte = ro->ro_rt;
if (rte && ((rte->rt_flags & RTF_UP) == 0 ||
rte->rt_ifp == NULL ||
!RT_LINK_IS_UP(rte->rt_ifp) ||
dst->sin_family != AF_INET ||
dst->sin_addr.s_addr != ip->ip_dst.s_addr)) {
if (!nortfree)
RTFREE(rte);
rte = ro->ro_rt = (struct rtentry *)NULL;
ro->ro_lle = (struct llentry *)NULL;
}
#ifdef IPFIREWALL_FORWARD
if (rte == NULL && fwd_tag == NULL) {
#else
if (rte == 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_INC(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), 0))) == NULL) {
IPSTAT_INC(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 (rte == 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
rte = ro->ro_rt;
}
if (rte == NULL ||
rte->rt_ifp == NULL ||
!RT_LINK_IS_UP(rte->rt_ifp)) {
#ifdef IPSEC
/*
* There is no route for this packet, but it is
* possible that a matching SPD entry exists.
*/
no_route_but_check_spd = 1;
mtu = 0; /* Silence GCC warning. */
goto sendit;
#endif
IPSTAT_INC(ips_noroute);
error = EHOSTUNREACH;
goto bad;
}
ia = ifatoia(rte->rt_ifa);
ifa_ref(&ia->ia_ifa);
ifp = rte->rt_ifp;
rte->rt_rmx.rmx_pksent++;
if (rte->rt_flags & RTF_GATEWAY)
dst = (struct sockaddr_in *)rte->rt_gateway;
if (rte->rt_flags & RTF_HOST)
isbroadcast = (rte->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 (rte != NULL && (rte->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 (rte->rt_rmx.rmx_mtu > ifp->if_mtu)
rte->rt_rmx.rmx_mtu = ifp->if_mtu;
mtu = rte->rt_rmx.rmx_mtu;
} else {
mtu = ifp->if_mtu;
}
/* Catch a possible divide by zero later. */
KASSERT(mtu > 0, ("%s: mtu %d <= 0, rte=%p (rt_flags=0x%08x) ifp=%p",
__func__, mtu, rte, (rte != NULL) ? rte->rt_flags : 0, ifp));
if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
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_INC(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;
}
if ((imo == NULL && in_mcast_loop) ||
(imo && imo->imo_multicast_loop)) {
/*
* Loop back multicast datagram if not expressly
* forbidden to do so, even if we are not a member
* of the group; ip_input() will filter it later,
* thus deferring a hash lookup and mutex acquisition
* at the expense of a cheap copy using m_copym().
*/
ip_mloopback(ifp, m, dst, hlen);
} else {
/*
* 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 (V_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 (!V_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. ip_input() will drop the copy if
* this host does not belong 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.
*/
n = ip->ip_len / mtu + 1; /* how many fragments ? */
if (
#ifdef ALTQ
(!ALTQ_IS_ENABLED(&ifp->if_snd)) &&
#endif /* ALTQ */
(ifp->if_snd.ifq_len + n) >= ifp->if_snd.ifq_maxlen ) {
error = ENOBUFS;
IPSTAT_INC(ips_odropped);
ifp->if_snd.ifq_drops += n;
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)) {
case 1:
goto bad;
case -1:
goto done;
case 0:
default:
break; /* Continue with packet processing. */
}
/*
* Check if there was a route for this packet; return error if not.
*/
if (no_route_but_check_spd) {
IPSTAT_INC(ips_noroute);
error = EHOSTUNREACH;
goto bad;
}
/* 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(&V_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(&V_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 = V_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;
#ifdef SCTP
if (m->m_pkthdr.csum_flags & CSUM_SCTP)
m->m_pkthdr.csum_flags |= CSUM_SCTP_VALID;
#endif
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 = V_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;
}
#ifdef SCTP
if (m->m_pkthdr.csum_flags & CSUM_SCTP)
m->m_pkthdr.csum_flags |= CSUM_SCTP_VALID;
#endif
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_INC(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;
}
#ifdef SCTP
if (sw_csum & CSUM_SCTP) {
sctp_delayed_cksum(m, (uint32_t)(ip->ip_hl << 2));
sw_csum &= ~CSUM_SCTP;
}
#endif
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);
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_INC(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);
} else
m_freem(m);
}
if (error == 0)
IPSTAT_INC(ips_fragmented);
done:
if (ro == &iproute && ro->ro_rt && !nortfree) {
RTFREE(ro->ro_rt);
}
if (ia != NULL)
ifa_free(&ia->ia_ifa);
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_INC(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;
}
#ifdef SCTP
if (m0->m_pkthdr.csum_flags & CSUM_SCTP &&
(if_hwassist_flags & CSUM_IP_FRAGS) == 0) {
sctp_delayed_cksum(m0, hlen);
m0->m_pkthdr.csum_flags &= ~CSUM_SCTP;
}
#endif
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_INC(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_copym().
*/
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_copym(m0, off, len, M_DONTWAIT);
if (m->m_next == NULL) { /* copy failed */
m_free(m);
error = ENOBUFS; /* ??? */
IPSTAT_INC(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_ADD(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) {
if ((sopt->sopt_level == SOL_SOCKET) &&
(sopt->sopt_name == SO_SETFIB)) {
inp->inp_inc.inc_fibnum = so->so_fibnum;
return (0);
}
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_BINDANY:
if (sopt->sopt_td != NULL) {
error = priv_check(sopt->sopt_td,
PRIV_NETINET_BINDANY);
if (error)
break;
}
/* FALLTHROUGH */
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;
case IP_BINDANY:
OPTSET(INP_BINDANY);
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 = ipsec_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:
case IP_BINDANY:
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;
case IP_BINDANY:
optval = OPTBIT(INP_BINDANY);
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 = ipsec_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;
/*
* Make a deep copy of the packet because we're going to
* modify the pack in order to generate checksums.
*/
copym = m_dup(m, M_DONTWAIT);
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);
#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
if_simloop(ifp, copym, dst->sin_family, 0);
}
}
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