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freebsd-dev/sys/netinet/ip_input.c
Andre Oppermann c21fd23260 Always compile PFIL_HOOKS into the kernel and remove the associated kernel 
compile option.  All FreeBSD packet filters now use the PFIL_HOOKS API and
thus it becomes a standard part of the network stack.

If no hooks are connected the entire packet filter hooks section and related
activities are jumped over.  This removes any performance impact if no hooks
are active.

Both OpenBSD and DragonFlyBSD have integrated PFIL_HOOKS permanently as well.
2004-08-27 15:16:24 +00:00

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52 KiB
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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.
*
* @(#)ip_input.c 8.2 (Berkeley) 1/4/94
* $FreeBSD$
*/
#include "opt_bootp.h"
#include "opt_ipfw.h"
#include "opt_ipstealth.h"
#include "opt_ipsec.h"
#include "opt_mac.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mac.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/syslog.h>
#include <sys/sysctl.h>
#include <net/pfil.h>
#include <net/if.h>
#include <net/if_types.h>
#include <net/if_var.h>
#include <net/if_dl.h>
#include <net/route.h>
#include <net/netisr.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/ip_var.h>
#include <netinet/ip_icmp.h>
#include <machine/in_cksum.h>
#include <sys/socketvar.h>
/* XXX: Temporary until ipfw_ether and ipfw_bridge are converted. */
#include <netinet/ip_fw.h>
#include <netinet/ip_dummynet.h>
#ifdef IPSEC
#include <netinet6/ipsec.h>
#include <netkey/key.h>
#endif
#ifdef FAST_IPSEC
#include <netipsec/ipsec.h>
#include <netipsec/key.h>
#endif
int rsvp_on = 0;
int ipforwarding = 0;
SYSCTL_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_RW,
&ipforwarding, 0, "Enable IP forwarding between interfaces");
static int ipsendredirects = 1; /* XXX */
SYSCTL_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_RW,
&ipsendredirects, 0, "Enable sending IP redirects");
int ip_defttl = IPDEFTTL;
SYSCTL_INT(_net_inet_ip, IPCTL_DEFTTL, ttl, CTLFLAG_RW,
&ip_defttl, 0, "Maximum TTL on IP packets");
static int ip_dosourceroute = 0;
SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW,
&ip_dosourceroute, 0, "Enable forwarding source routed IP packets");
static int ip_acceptsourceroute = 0;
SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute,
CTLFLAG_RW, &ip_acceptsourceroute, 0,
"Enable accepting source routed IP packets");
int ip_doopts = 1; /* 0 = ignore, 1 = process, 2 = reject */
SYSCTL_INT(_net_inet_ip, OID_AUTO, process_options, CTLFLAG_RW,
&ip_doopts, 0, "Enable IP options processing ([LS]SRR, RR, TS)");
static int ip_keepfaith = 0;
SYSCTL_INT(_net_inet_ip, IPCTL_KEEPFAITH, keepfaith, CTLFLAG_RW,
&ip_keepfaith, 0,
"Enable packet capture for FAITH IPv4->IPv6 translater daemon");
static int nipq = 0; /* total # of reass queues */
static int maxnipq;
SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragpackets, CTLFLAG_RW,
&maxnipq, 0,
"Maximum number of IPv4 fragment reassembly queue entries");
static int maxfragsperpacket;
SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_RW,
&maxfragsperpacket, 0,
"Maximum number of IPv4 fragments allowed per packet");
static int ip_sendsourcequench = 0;
SYSCTL_INT(_net_inet_ip, OID_AUTO, sendsourcequench, CTLFLAG_RW,
&ip_sendsourcequench, 0,
"Enable the transmission of source quench packets");
int ip_do_randomid = 0;
SYSCTL_INT(_net_inet_ip, OID_AUTO, random_id, CTLFLAG_RW,
&ip_do_randomid, 0,
"Assign random ip_id values");
/*
* XXX - Setting ip_checkinterface mostly implements the receive side of
* the Strong ES model described in RFC 1122, but since the routing table
* and transmit implementation do not implement the Strong ES model,
* setting this to 1 results in an odd hybrid.
*
* XXX - ip_checkinterface currently must be disabled if you use ipnat
* to translate the destination address to another local interface.
*
* XXX - ip_checkinterface must be disabled if you add IP aliases
* to the loopback interface instead of the interface where the
* packets for those addresses are received.
*/
static int ip_checkinterface = 1;
SYSCTL_INT(_net_inet_ip, OID_AUTO, check_interface, CTLFLAG_RW,
&ip_checkinterface, 0, "Verify packet arrives on correct interface");
#ifdef DIAGNOSTIC
static int ipprintfs = 0;
#endif
struct pfil_head inet_pfil_hook; /* Packet filter hooks */
static struct ifqueue ipintrq;
static int ipqmaxlen = IFQ_MAXLEN;
extern struct domain inetdomain;
extern struct protosw inetsw[];
u_char ip_protox[IPPROTO_MAX];
struct in_ifaddrhead in_ifaddrhead; /* first inet address */
struct in_ifaddrhashhead *in_ifaddrhashtbl; /* inet addr hash table */
u_long in_ifaddrhmask; /* mask for hash table */
SYSCTL_INT(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_queue_maxlen, CTLFLAG_RW,
&ipintrq.ifq_maxlen, 0, "Maximum size of the IP input queue");
SYSCTL_INT(_net_inet_ip, IPCTL_INTRQDROPS, intr_queue_drops, CTLFLAG_RD,
&ipintrq.ifq_drops, 0, "Number of packets dropped from the IP input queue");
struct ipstat ipstat;
SYSCTL_STRUCT(_net_inet_ip, IPCTL_STATS, stats, CTLFLAG_RW,
&ipstat, ipstat, "IP statistics (struct ipstat, netinet/ip_var.h)");
/* Packet reassembly stuff */
#define IPREASS_NHASH_LOG2 6
#define IPREASS_NHASH (1 << IPREASS_NHASH_LOG2)
#define IPREASS_HMASK (IPREASS_NHASH - 1)
#define IPREASS_HASH(x,y) \
(((((x) & 0xF) | ((((x) >> 8) & 0xF) << 4)) ^ (y)) & IPREASS_HMASK)
static TAILQ_HEAD(ipqhead, ipq) ipq[IPREASS_NHASH];
struct mtx ipqlock;
#define IPQ_LOCK() mtx_lock(&ipqlock)
#define IPQ_UNLOCK() mtx_unlock(&ipqlock)
#define IPQ_LOCK_INIT() mtx_init(&ipqlock, "ipqlock", NULL, MTX_DEF)
#define IPQ_LOCK_ASSERT() mtx_assert(&ipqlock, MA_OWNED)
#ifdef IPCTL_DEFMTU
SYSCTL_INT(_net_inet_ip, IPCTL_DEFMTU, mtu, CTLFLAG_RW,
&ip_mtu, 0, "Default MTU");
#endif
#ifdef IPSTEALTH
int ipstealth = 0;
SYSCTL_INT(_net_inet_ip, OID_AUTO, stealth, CTLFLAG_RW,
&ipstealth, 0, "");
#endif
/*
* ipfw_ether and ipfw_bridge hooks.
* XXX: Temporary until those are converted to pfil_hooks as well.
*/
ip_fw_chk_t *ip_fw_chk_ptr = NULL;
ip_dn_io_t *ip_dn_io_ptr = NULL;
int fw_enable = 1;
int fw_one_pass = 1;
/*
* XXX this is ugly -- the following two global variables are
* used to store packet state while it travels through the stack.
* Note that the code even makes assumptions on the size and
* alignment of fields inside struct ip_srcrt so e.g. adding some
* fields will break the code. This needs to be fixed.
*
* We need to save the IP options in case a protocol wants to respond
* to an incoming packet over the same route if the packet got here
* using IP source routing. This allows connection establishment and
* maintenance when the remote end is on a network that is not known
* to us.
* XXX: Broken on SMP and possibly preemption!
*/
static int ip_nhops = 0;
static struct ip_srcrt {
struct in_addr dst; /* final destination */
char nop; /* one NOP to align */
char srcopt[IPOPT_OFFSET + 1]; /* OPTVAL, OLEN and OFFSET */
struct in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
} ip_srcrt;
static void save_rte(u_char *, struct in_addr);
static int ip_dooptions(struct mbuf *m, int);
static void ip_forward(struct mbuf *m, int srcrt);
static void ip_freef(struct ipqhead *, struct ipq *);
/*
* IP initialization: fill in IP protocol switch table.
* All protocols not implemented in kernel go to raw IP protocol handler.
*/
void
ip_init()
{
register struct protosw *pr;
register int i;
TAILQ_INIT(&in_ifaddrhead);
in_ifaddrhashtbl = hashinit(INADDR_NHASH, M_IFADDR, &in_ifaddrhmask);
pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
if (pr == 0)
panic("ip_init");
for (i = 0; i < IPPROTO_MAX; i++)
ip_protox[i] = pr - inetsw;
for (pr = inetdomain.dom_protosw;
pr < inetdomain.dom_protoswNPROTOSW; pr++)
if (pr->pr_domain->dom_family == PF_INET &&
pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
ip_protox[pr->pr_protocol] = pr - inetsw;
/* Initialize packet filter hooks. */
inet_pfil_hook.ph_type = PFIL_TYPE_AF;
inet_pfil_hook.ph_af = AF_INET;
if ((i = pfil_head_register(&inet_pfil_hook)) != 0)
printf("%s: WARNING: unable to register pfil hook, "
"error %d\n", __func__, i);
IPQ_LOCK_INIT();
for (i = 0; i < IPREASS_NHASH; i++)
TAILQ_INIT(&ipq[i]);
maxnipq = nmbclusters / 32;
maxfragsperpacket = 16;
ip_id = time_second & 0xffff;
ipintrq.ifq_maxlen = ipqmaxlen;
mtx_init(&ipintrq.ifq_mtx, "ip_inq", NULL, MTX_DEF);
netisr_register(NETISR_IP, ip_input, &ipintrq, NETISR_MPSAFE);
}
/*
* Ip input routine. Checksum and byte swap header. If fragmented
* try to reassemble. Process options. Pass to next level.
*/
void
ip_input(struct mbuf *m)
{
struct ip *ip = NULL;
struct in_ifaddr *ia = NULL;
struct ifaddr *ifa;
int checkif, hlen = 0;
u_short sum;
int dchg = 0; /* dest changed after fw */
struct in_addr odst; /* original dst address */
#ifdef FAST_IPSEC
struct m_tag *mtag;
struct tdb_ident *tdbi;
struct secpolicy *sp;
int s, error;
#endif /* FAST_IPSEC */
M_ASSERTPKTHDR(m);
if (m->m_flags & M_FASTFWD_OURS) {
/*
* ip_fastforward firewall changed dest to local.
* We expect ip_len and ip_off in host byte order.
*/
m->m_flags &= ~M_FASTFWD_OURS; /* for reflected mbufs */
/* Set up some basic stuff */
ip = mtod(m, struct ip *);
hlen = ip->ip_hl << 2;
goto ours;
}
ipstat.ips_total++;
if (m->m_pkthdr.len < sizeof(struct ip))
goto tooshort;
if (m->m_len < sizeof (struct ip) &&
(m = m_pullup(m, sizeof (struct ip))) == NULL) {
ipstat.ips_toosmall++;
return;
}
ip = mtod(m, struct ip *);
if (ip->ip_v != IPVERSION) {
ipstat.ips_badvers++;
goto bad;
}
hlen = ip->ip_hl << 2;
if (hlen < sizeof(struct ip)) { /* minimum header length */
ipstat.ips_badhlen++;
goto bad;
}
if (hlen > m->m_len) {
if ((m = m_pullup(m, hlen)) == NULL) {
ipstat.ips_badhlen++;
return;
}
ip = mtod(m, struct ip *);
}
/* 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 ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) {
ipstat.ips_badaddr++;
goto bad;
}
}
if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) {
sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID);
} else {
if (hlen == sizeof(struct ip)) {
sum = in_cksum_hdr(ip);
} else {
sum = in_cksum(m, hlen);
}
}
if (sum) {
ipstat.ips_badsum++;
goto bad;
}
#ifdef ALTQ
if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0)
/* packet is dropped by traffic conditioner */
return;
#endif
/*
* Convert fields to host representation.
*/
ip->ip_len = ntohs(ip->ip_len);
if (ip->ip_len < hlen) {
ipstat.ips_badlen++;
goto bad;
}
ip->ip_off = ntohs(ip->ip_off);
/*
* Check that the amount of data in the buffers
* is as at least much as the IP header would have us expect.
* Trim mbufs if longer than we expect.
* Drop packet if shorter than we expect.
*/
if (m->m_pkthdr.len < ip->ip_len) {
tooshort:
ipstat.ips_tooshort++;
goto bad;
}
if (m->m_pkthdr.len > ip->ip_len) {
if (m->m_len == m->m_pkthdr.len) {
m->m_len = ip->ip_len;
m->m_pkthdr.len = ip->ip_len;
} else
m_adj(m, ip->ip_len - m->m_pkthdr.len);
}
#if defined(IPSEC) && !defined(IPSEC_FILTERGIF)
/*
* Bypass packet filtering for packets from a tunnel (gif).
*/
if (ipsec_getnhist(m))
goto passin;
#endif
#if defined(FAST_IPSEC) && !defined(IPSEC_FILTERGIF)
/*
* Bypass packet filtering for packets from a tunnel (gif).
*/
if (m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL)
goto passin;
#endif
/*
* Run through list of hooks for input packets.
*
* NB: Beware of the destination address changing (e.g.
* by NAT rewriting). When this happens, tell
* ip_forward to do the right thing.
*/
/* Jump over all PFIL processing if hooks are not active. */
if (inet_pfil_hook.ph_busy_count == -1)
goto passin;
odst = ip->ip_dst;
if (pfil_run_hooks(&inet_pfil_hook, &m, m->m_pkthdr.rcvif,
PFIL_IN) != 0)
return;
if (m == NULL) /* consumed by filter */
return;
ip = mtod(m, struct ip *);
dchg = (odst.s_addr != ip->ip_dst.s_addr);
#ifdef IPFIREWALL_FORWARD
if (m->m_flags & M_FASTFWD_OURS) {
m->m_flags &= ~M_FASTFWD_OURS;
goto ours;
}
dchg = (m_tag_find(m, PACKET_TAG_IPFORWARD, NULL) != NULL);
#endif /* IPFIREWALL_FORWARD */
passin:
/*
* Process options and, if not destined for us,
* ship it on. ip_dooptions returns 1 when an
* error was detected (causing an icmp message
* to be sent and the original packet to be freed).
*/
if (hlen > sizeof (struct ip) && ip_dooptions(m, 0))
return;
/* greedy RSVP, snatches any PATH packet of the RSVP protocol and no
* matter if it is destined to another node, or whether it is
* a multicast one, RSVP wants it! and prevents it from being forwarded
* anywhere else. Also checks if the rsvp daemon is running before
* grabbing the packet.
*/
if (rsvp_on && ip->ip_p==IPPROTO_RSVP)
goto ours;
/*
* Check our list of addresses, to see if the packet is for us.
* If we don't have any addresses, assume any unicast packet
* we receive might be for us (and let the upper layers deal
* with it).
*/
if (TAILQ_EMPTY(&in_ifaddrhead) &&
(m->m_flags & (M_MCAST|M_BCAST)) == 0)
goto ours;
/*
* Enable a consistency check between the destination address
* and the arrival interface for a unicast packet (the RFC 1122
* strong ES model) if IP forwarding is disabled and the packet
* is not locally generated and the packet is not subject to
* 'ipfw fwd'.
*
* XXX - Checking also should be disabled if the destination
* address is ipnat'ed to a different interface.
*
* XXX - Checking is incompatible with IP aliases added
* to the loopback interface instead of the interface where
* the packets are received.
*/
checkif = ip_checkinterface && (ipforwarding == 0) &&
m->m_pkthdr.rcvif != NULL &&
((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) &&
(dchg == 0);
/*
* Check for exact addresses in the hash bucket.
*/
LIST_FOREACH(ia, INADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
/*
* If the address matches, verify that the packet
* arrived via the correct interface if checking is
* enabled.
*/
if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr &&
(!checkif || ia->ia_ifp == m->m_pkthdr.rcvif))
goto ours;
}
/*
* Check for broadcast addresses.
*
* Only accept broadcast packets that arrive via the matching
* interface. Reception of forwarded directed broadcasts would
* be handled via ip_forward() and ether_output() with the loopback
* into the stack for SIMPLEX interfaces handled by ether_output().
*/
if (m->m_pkthdr.rcvif != NULL &&
m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) {
if (ifa->ifa_addr->sa_family != AF_INET)
continue;
ia = ifatoia(ifa);
if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
ip->ip_dst.s_addr)
goto ours;
if (ia->ia_netbroadcast.s_addr == ip->ip_dst.s_addr)
goto ours;
#ifdef BOOTP_COMPAT
if (IA_SIN(ia)->sin_addr.s_addr == INADDR_ANY)
goto ours;
#endif
}
}
if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
struct in_multi *inm;
if (ip_mrouter) {
/*
* If we are acting as a multicast router, all
* incoming multicast packets are passed to the
* kernel-level multicast forwarding function.
* The packet is returned (relatively) intact; if
* ip_mforward() returns a non-zero value, the packet
* must be discarded, else it may be accepted below.
*/
if (ip_mforward &&
ip_mforward(ip, m->m_pkthdr.rcvif, m, 0) != 0) {
ipstat.ips_cantforward++;
m_freem(m);
return;
}
/*
* The process-level routing daemon needs to receive
* all multicast IGMP packets, whether or not this
* host belongs to their destination groups.
*/
if (ip->ip_p == IPPROTO_IGMP)
goto ours;
ipstat.ips_forward++;
}
/*
* See if we belong to the destination multicast group on the
* arrival interface.
*/
IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
if (inm == NULL) {
ipstat.ips_notmember++;
m_freem(m);
return;
}
goto ours;
}
if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST)
goto ours;
if (ip->ip_dst.s_addr == INADDR_ANY)
goto ours;
/*
* FAITH(Firewall Aided Internet Translator)
*/
if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
if (ip_keepfaith) {
if (ip->ip_p == IPPROTO_TCP || ip->ip_p == IPPROTO_ICMP)
goto ours;
}
m_freem(m);
return;
}
/*
* Not for us; forward if possible and desirable.
*/
if (ipforwarding == 0) {
ipstat.ips_cantforward++;
m_freem(m);
} else {
#ifdef IPSEC
/*
* Enforce inbound IPsec SPD.
*/
if (ipsec4_in_reject(m, NULL)) {
ipsecstat.in_polvio++;
goto bad;
}
#endif /* IPSEC */
#ifdef FAST_IPSEC
mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
s = splnet();
if (mtag != NULL) {
tdbi = (struct tdb_ident *)(mtag + 1);
sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
} else {
sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
IP_FORWARDING, &error);
}
if (sp == NULL) { /* NB: can happen if error */
splx(s);
/*XXX error stat???*/
DPRINTF(("ip_input: no SP for forwarding\n")); /*XXX*/
goto bad;
}
/*
* Check security policy against packet attributes.
*/
error = ipsec_in_reject(sp, m);
KEY_FREESP(&sp);
splx(s);
if (error) {
ipstat.ips_cantforward++;
goto bad;
}
#endif /* FAST_IPSEC */
ip_forward(m, dchg);
}
return;
ours:
#ifdef IPSTEALTH
/*
* IPSTEALTH: Process non-routing options only
* if the packet is destined for us.
*/
if (ipstealth && hlen > sizeof (struct ip) &&
ip_dooptions(m, 1))
return;
#endif /* IPSTEALTH */
/* Count the packet in the ip address stats */
if (ia != NULL) {
ia->ia_ifa.if_ipackets++;
ia->ia_ifa.if_ibytes += m->m_pkthdr.len;
}
/*
* Attempt reassembly; if it succeeds, proceed.
* ip_reass() will return a different mbuf.
*/
if (ip->ip_off & (IP_MF | IP_OFFMASK)) {
m = ip_reass(m);
if (m == NULL)
return;
ip = mtod(m, struct ip *);
/* Get the header length of the reassembled packet */
hlen = ip->ip_hl << 2;
}
/*
* Further protocols expect the packet length to be w/o the
* IP header.
*/
ip->ip_len -= hlen;
#ifdef IPSEC
/*
* enforce IPsec policy checking if we are seeing last header.
* note that we do not visit this with protocols with pcb layer
* code - like udp/tcp/raw ip.
*/
if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0 &&
ipsec4_in_reject(m, NULL)) {
ipsecstat.in_polvio++;
goto bad;
}
#endif
#if FAST_IPSEC
/*
* enforce IPsec policy checking if we are seeing last header.
* note that we do not visit this with protocols with pcb layer
* code - like udp/tcp/raw ip.
*/
if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
/*
* Check if the packet has already had IPsec processing
* done. If so, then just pass it along. This tag gets
* set during AH, ESP, etc. input handling, before the
* packet is returned to the ip input queue for delivery.
*/
mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
s = splnet();
if (mtag != NULL) {
tdbi = (struct tdb_ident *)(mtag + 1);
sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
} else {
sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
IP_FORWARDING, &error);
}
if (sp != NULL) {
/*
* Check security policy against packet attributes.
*/
error = ipsec_in_reject(sp, m);
KEY_FREESP(&sp);
} else {
/* XXX error stat??? */
error = EINVAL;
DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
goto bad;
}
splx(s);
if (error)
goto bad;
}
#endif /* FAST_IPSEC */
/*
* Switch out to protocol's input routine.
*/
ipstat.ips_delivered++;
(*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen);
return;
bad:
m_freem(m);
}
/*
* Take incoming datagram fragment and try to reassemble it into
* whole datagram. If the argument is the first fragment or one
* in between the function will return NULL and store the mbuf
* in the fragment chain. If the argument is the last fragment
* the packet will be reassembled and the pointer to the new
* mbuf returned for further processing. Only m_tags attached
* to the first packet/fragment are preserved.
* The IP header is *NOT* adjusted out of iplen.
*/
struct mbuf *
ip_reass(struct mbuf *m)
{
struct ip *ip;
struct mbuf *p, *q, *nq, *t;
struct ipq *fp = NULL;
struct ipqhead *head;
int i, hlen, next;
u_int8_t ecn, ecn0;
u_short hash;
/* If maxnipq is 0, never accept fragments. */
if (maxnipq == 0) {
ipstat.ips_fragments++;
ipstat.ips_fragdropped++;
m_freem(m);
return (NULL);
}
ip = mtod(m, struct ip *);
hlen = ip->ip_hl << 2;
hash = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id);
head = &ipq[hash];
IPQ_LOCK();
/*
* Look for queue of fragments
* of this datagram.
*/
TAILQ_FOREACH(fp, head, ipq_list)
if (ip->ip_id == fp->ipq_id &&
ip->ip_src.s_addr == fp->ipq_src.s_addr &&
ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
#ifdef MAC
mac_fragment_match(m, fp) &&
#endif
ip->ip_p == fp->ipq_p)
goto found;
fp = NULL;
/*
* Enforce upper bound on number of fragmented packets
* for which we attempt reassembly;
* If maxnipq is -1, accept all fragments without limitation.
*/
if ((nipq > maxnipq) && (maxnipq > 0)) {
/*
* drop something from the tail of the current queue
* before proceeding further
*/
struct ipq *q = TAILQ_LAST(head, ipqhead);
if (q == NULL) { /* gak */
for (i = 0; i < IPREASS_NHASH; i++) {
struct ipq *r = TAILQ_LAST(&ipq[i], ipqhead);
if (r) {
ipstat.ips_fragtimeout += r->ipq_nfrags;
ip_freef(&ipq[i], r);
break;
}
}
} else {
ipstat.ips_fragtimeout += q->ipq_nfrags;
ip_freef(head, q);
}
}
found:
/*
* Adjust ip_len to not reflect header,
* convert offset of this to bytes.
*/
ip->ip_len -= hlen;
if (ip->ip_off & IP_MF) {
/*
* Make sure that fragments have a data length
* that's a non-zero multiple of 8 bytes.
*/
if (ip->ip_len == 0 || (ip->ip_len & 0x7) != 0) {
ipstat.ips_toosmall++; /* XXX */
goto dropfrag;
}
m->m_flags |= M_FRAG;
} else
m->m_flags &= ~M_FRAG;
ip->ip_off <<= 3;
/*
* Attempt reassembly; if it succeeds, proceed.
* ip_reass() will return a different mbuf.
*/
ipstat.ips_fragments++;
m->m_pkthdr.header = ip;
/* Previous ip_reass() started here. */
/*
* Presence of header sizes in mbufs
* would confuse code below.
*/
m->m_data += hlen;
m->m_len -= hlen;
/*
* If first fragment to arrive, create a reassembly queue.
*/
if (fp == NULL) {
if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL)
goto dropfrag;
fp = mtod(t, struct ipq *);
#ifdef MAC
if (mac_init_ipq(fp, M_NOWAIT) != 0) {
m_free(t);
goto dropfrag;
}
mac_create_ipq(m, fp);
#endif
TAILQ_INSERT_HEAD(head, fp, ipq_list);
nipq++;
fp->ipq_nfrags = 1;
fp->ipq_ttl = IPFRAGTTL;
fp->ipq_p = ip->ip_p;
fp->ipq_id = ip->ip_id;
fp->ipq_src = ip->ip_src;
fp->ipq_dst = ip->ip_dst;
fp->ipq_frags = m;
m->m_nextpkt = NULL;
goto inserted;
} else {
fp->ipq_nfrags++;
#ifdef MAC
mac_update_ipq(m, fp);
#endif
}
#define GETIP(m) ((struct ip*)((m)->m_pkthdr.header))
/*
* Handle ECN by comparing this segment with the first one;
* if CE is set, do not lose CE.
* drop if CE and not-ECT are mixed for the same packet.
*/
ecn = ip->ip_tos & IPTOS_ECN_MASK;
ecn0 = GETIP(fp->ipq_frags)->ip_tos & IPTOS_ECN_MASK;
if (ecn == IPTOS_ECN_CE) {
if (ecn0 == IPTOS_ECN_NOTECT)
goto dropfrag;
if (ecn0 != IPTOS_ECN_CE)
GETIP(fp->ipq_frags)->ip_tos |= IPTOS_ECN_CE;
}
if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT)
goto dropfrag;
/*
* Find a segment which begins after this one does.
*/
for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt)
if (GETIP(q)->ip_off > ip->ip_off)
break;
/*
* If there is a preceding segment, it may provide some of
* our data already. If so, drop the data from the incoming
* segment. If it provides all of our data, drop us, otherwise
* stick new segment in the proper place.
*
* If some of the data is dropped from the the preceding
* segment, then it's checksum is invalidated.
*/
if (p) {
i = GETIP(p)->ip_off + GETIP(p)->ip_len - ip->ip_off;
if (i > 0) {
if (i >= ip->ip_len)
goto dropfrag;
m_adj(m, i);
m->m_pkthdr.csum_flags = 0;
ip->ip_off += i;
ip->ip_len -= i;
}
m->m_nextpkt = p->m_nextpkt;
p->m_nextpkt = m;
} else {
m->m_nextpkt = fp->ipq_frags;
fp->ipq_frags = m;
}
/*
* While we overlap succeeding segments trim them or,
* if they are completely covered, dequeue them.
*/
for (; q != NULL && ip->ip_off + ip->ip_len > GETIP(q)->ip_off;
q = nq) {
i = (ip->ip_off + ip->ip_len) - GETIP(q)->ip_off;
if (i < GETIP(q)->ip_len) {
GETIP(q)->ip_len -= i;
GETIP(q)->ip_off += i;
m_adj(q, i);
q->m_pkthdr.csum_flags = 0;
break;
}
nq = q->m_nextpkt;
m->m_nextpkt = nq;
ipstat.ips_fragdropped++;
fp->ipq_nfrags--;
m_freem(q);
}
inserted:
/*
* Check for complete reassembly and perform frag per packet
* limiting.
*
* Frag limiting is performed here so that the nth frag has
* a chance to complete the packet before we drop the packet.
* As a result, n+1 frags are actually allowed per packet, but
* only n will ever be stored. (n = maxfragsperpacket.)
*
*/
next = 0;
for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) {
if (GETIP(q)->ip_off != next) {
if (fp->ipq_nfrags > maxfragsperpacket) {
ipstat.ips_fragdropped += fp->ipq_nfrags;
ip_freef(head, fp);
}
goto done;
}
next += GETIP(q)->ip_len;
}
/* Make sure the last packet didn't have the IP_MF flag */
if (p->m_flags & M_FRAG) {
if (fp->ipq_nfrags > maxfragsperpacket) {
ipstat.ips_fragdropped += fp->ipq_nfrags;
ip_freef(head, fp);
}
goto done;
}
/*
* Reassembly is complete. Make sure the packet is a sane size.
*/
q = fp->ipq_frags;
ip = GETIP(q);
if (next + (ip->ip_hl << 2) > IP_MAXPACKET) {
ipstat.ips_toolong++;
ipstat.ips_fragdropped += fp->ipq_nfrags;
ip_freef(head, fp);
goto done;
}
/*
* Concatenate fragments.
*/
m = q;
t = m->m_next;
m->m_next = 0;
m_cat(m, t);
nq = q->m_nextpkt;
q->m_nextpkt = 0;
for (q = nq; q != NULL; q = nq) {
nq = q->m_nextpkt;
q->m_nextpkt = NULL;
m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags;
m->m_pkthdr.csum_data += q->m_pkthdr.csum_data;
m_cat(m, q);
}
#ifdef MAC
mac_create_datagram_from_ipq(fp, m);
mac_destroy_ipq(fp);
#endif
/*
* Create header for new ip packet by modifying header of first
* packet; dequeue and discard fragment reassembly header.
* Make header visible.
*/
ip->ip_len = (ip->ip_hl << 2) + next;
ip->ip_src = fp->ipq_src;
ip->ip_dst = fp->ipq_dst;
TAILQ_REMOVE(head, fp, ipq_list);
nipq--;
(void) m_free(dtom(fp));
m->m_len += (ip->ip_hl << 2);
m->m_data -= (ip->ip_hl << 2);
/* some debugging cruft by sklower, below, will go away soon */
if (m->m_flags & M_PKTHDR) /* XXX this should be done elsewhere */
m_fixhdr(m);
ipstat.ips_reassembled++;
IPQ_UNLOCK();
return (m);
dropfrag:
ipstat.ips_fragdropped++;
if (fp != NULL)
fp->ipq_nfrags--;
m_freem(m);
done:
IPQ_UNLOCK();
return (NULL);
#undef GETIP
}
/*
* Free a fragment reassembly header and all
* associated datagrams.
*/
static void
ip_freef(fhp, fp)
struct ipqhead *fhp;
struct ipq *fp;
{
register struct mbuf *q;
IPQ_LOCK_ASSERT();
while (fp->ipq_frags) {
q = fp->ipq_frags;
fp->ipq_frags = q->m_nextpkt;
m_freem(q);
}
TAILQ_REMOVE(fhp, fp, ipq_list);
(void) m_free(dtom(fp));
nipq--;
}
/*
* IP timer processing;
* if a timer expires on a reassembly
* queue, discard it.
*/
void
ip_slowtimo()
{
register struct ipq *fp;
int s = splnet();
int i;
IPQ_LOCK();
for (i = 0; i < IPREASS_NHASH; i++) {
for(fp = TAILQ_FIRST(&ipq[i]); fp;) {
struct ipq *fpp;
fpp = fp;
fp = TAILQ_NEXT(fp, ipq_list);
if(--fpp->ipq_ttl == 0) {
ipstat.ips_fragtimeout += fpp->ipq_nfrags;
ip_freef(&ipq[i], fpp);
}
}
}
/*
* If we are over the maximum number of fragments
* (due to the limit being lowered), drain off
* enough to get down to the new limit.
*/
if (maxnipq >= 0 && nipq > maxnipq) {
for (i = 0; i < IPREASS_NHASH; i++) {
while (nipq > maxnipq && !TAILQ_EMPTY(&ipq[i])) {
ipstat.ips_fragdropped +=
TAILQ_FIRST(&ipq[i])->ipq_nfrags;
ip_freef(&ipq[i], TAILQ_FIRST(&ipq[i]));
}
}
}
IPQ_UNLOCK();
splx(s);
}
/*
* Drain off all datagram fragments.
*/
void
ip_drain()
{
int i;
IPQ_LOCK();
for (i = 0; i < IPREASS_NHASH; i++) {
while(!TAILQ_EMPTY(&ipq[i])) {
ipstat.ips_fragdropped +=
TAILQ_FIRST(&ipq[i])->ipq_nfrags;
ip_freef(&ipq[i], TAILQ_FIRST(&ipq[i]));
}
}
IPQ_UNLOCK();
in_rtqdrain();
}
/*
* Do option processing on a datagram,
* possibly discarding it if bad options are encountered,
* or forwarding it if source-routed.
* The pass argument is used when operating in the IPSTEALTH
* mode to tell what options to process:
* [LS]SRR (pass 0) or the others (pass 1).
* The reason for as many as two passes is that when doing IPSTEALTH,
* non-routing options should be processed only if the packet is for us.
* Returns 1 if packet has been forwarded/freed,
* 0 if the packet should be processed further.
*/
static int
ip_dooptions(struct mbuf *m, int pass)
{
struct ip *ip = mtod(m, struct ip *);
u_char *cp;
struct in_ifaddr *ia;
int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
struct in_addr *sin, dst;
n_time ntime;
struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
/* ignore or reject packets with IP options */
if (ip_doopts == 0)
return 0;
else if (ip_doopts == 2) {
type = ICMP_UNREACH;
code = ICMP_UNREACH_FILTER_PROHIB;
goto bad;
}
dst = ip->ip_dst;
cp = (u_char *)(ip + 1);
cnt = (ip->ip_hl << 2) - sizeof (struct ip);
for (; cnt > 0; cnt -= optlen, cp += optlen) {
opt = cp[IPOPT_OPTVAL];
if (opt == IPOPT_EOL)
break;
if (opt == IPOPT_NOP)
optlen = 1;
else {
if (cnt < IPOPT_OLEN + sizeof(*cp)) {
code = &cp[IPOPT_OLEN] - (u_char *)ip;
goto bad;
}
optlen = cp[IPOPT_OLEN];
if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
code = &cp[IPOPT_OLEN] - (u_char *)ip;
goto bad;
}
}
switch (opt) {
default:
break;
/*
* Source routing with record.
* Find interface with current destination address.
* If none on this machine then drop if strictly routed,
* or do nothing if loosely routed.
* Record interface address and bring up next address
* component. If strictly routed make sure next
* address is on directly accessible net.
*/
case IPOPT_LSRR:
case IPOPT_SSRR:
#ifdef IPSTEALTH
if (ipstealth && pass > 0)
break;
#endif
if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
code = &cp[IPOPT_OLEN] - (u_char *)ip;
goto bad;
}
if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
code = &cp[IPOPT_OFFSET] - (u_char *)ip;
goto bad;
}
ipaddr.sin_addr = ip->ip_dst;
ia = (struct in_ifaddr *)
ifa_ifwithaddr((struct sockaddr *)&ipaddr);
if (ia == NULL) {
if (opt == IPOPT_SSRR) {
type = ICMP_UNREACH;
code = ICMP_UNREACH_SRCFAIL;
goto bad;
}
if (!ip_dosourceroute)
goto nosourcerouting;
/*
* Loose routing, and not at next destination
* yet; nothing to do except forward.
*/
break;
}
off--; /* 0 origin */
if (off > optlen - (int)sizeof(struct in_addr)) {
/*
* End of source route. Should be for us.
*/
if (!ip_acceptsourceroute)
goto nosourcerouting;
save_rte(cp, ip->ip_src);
break;
}
#ifdef IPSTEALTH
if (ipstealth)
goto dropit;
#endif
if (!ip_dosourceroute) {
if (ipforwarding) {
char buf[16]; /* aaa.bbb.ccc.ddd\0 */
/*
* Acting as a router, so generate ICMP
*/
nosourcerouting:
strcpy(buf, inet_ntoa(ip->ip_dst));
log(LOG_WARNING,
"attempted source route from %s to %s\n",
inet_ntoa(ip->ip_src), buf);
type = ICMP_UNREACH;
code = ICMP_UNREACH_SRCFAIL;
goto bad;
} else {
/*
* Not acting as a router, so silently drop.
*/
#ifdef IPSTEALTH
dropit:
#endif
ipstat.ips_cantforward++;
m_freem(m);
return (1);
}
}
/*
* locate outgoing interface
*/
(void)memcpy(&ipaddr.sin_addr, cp + off,
sizeof(ipaddr.sin_addr));
if (opt == IPOPT_SSRR) {
#define INA struct in_ifaddr *
#define SA struct sockaddr *
if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == NULL)
ia = (INA)ifa_ifwithnet((SA)&ipaddr);
} else
ia = ip_rtaddr(ipaddr.sin_addr);
if (ia == NULL) {
type = ICMP_UNREACH;
code = ICMP_UNREACH_SRCFAIL;
goto bad;
}
ip->ip_dst = ipaddr.sin_addr;
(void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
sizeof(struct in_addr));
cp[IPOPT_OFFSET] += sizeof(struct in_addr);
/*
* Let ip_intr's mcast routing check handle mcast pkts
*/
forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
break;
case IPOPT_RR:
#ifdef IPSTEALTH
if (ipstealth && pass == 0)
break;
#endif
if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
code = &cp[IPOPT_OFFSET] - (u_char *)ip;
goto bad;
}
if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
code = &cp[IPOPT_OFFSET] - (u_char *)ip;
goto bad;
}
/*
* If no space remains, ignore.
*/
off--; /* 0 origin */
if (off > optlen - (int)sizeof(struct in_addr))
break;
(void)memcpy(&ipaddr.sin_addr, &ip->ip_dst,
sizeof(ipaddr.sin_addr));
/*
* locate outgoing interface; if we're the destination,
* use the incoming interface (should be same).
*/
if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == NULL &&
(ia = ip_rtaddr(ipaddr.sin_addr)) == NULL) {
type = ICMP_UNREACH;
code = ICMP_UNREACH_HOST;
goto bad;
}
(void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
sizeof(struct in_addr));
cp[IPOPT_OFFSET] += sizeof(struct in_addr);
break;
case IPOPT_TS:
#ifdef IPSTEALTH
if (ipstealth && pass == 0)
break;
#endif
code = cp - (u_char *)ip;
if (optlen < 4 || optlen > 40) {
code = &cp[IPOPT_OLEN] - (u_char *)ip;
goto bad;
}
if ((off = cp[IPOPT_OFFSET]) < 5) {
code = &cp[IPOPT_OLEN] - (u_char *)ip;
goto bad;
}
if (off > optlen - (int)sizeof(int32_t)) {
cp[IPOPT_OFFSET + 1] += (1 << 4);
if ((cp[IPOPT_OFFSET + 1] & 0xf0) == 0) {
code = &cp[IPOPT_OFFSET] - (u_char *)ip;
goto bad;
}
break;
}
off--; /* 0 origin */
sin = (struct in_addr *)(cp + off);
switch (cp[IPOPT_OFFSET + 1] & 0x0f) {
case IPOPT_TS_TSONLY:
break;
case IPOPT_TS_TSANDADDR:
if (off + sizeof(n_time) +
sizeof(struct in_addr) > optlen) {
code = &cp[IPOPT_OFFSET] - (u_char *)ip;
goto bad;
}
ipaddr.sin_addr = dst;
ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
m->m_pkthdr.rcvif);
if (ia == NULL)
continue;
(void)memcpy(sin, &IA_SIN(ia)->sin_addr,
sizeof(struct in_addr));
cp[IPOPT_OFFSET] += sizeof(struct in_addr);
off += sizeof(struct in_addr);
break;
case IPOPT_TS_PRESPEC:
if (off + sizeof(n_time) +
sizeof(struct in_addr) > optlen) {
code = &cp[IPOPT_OFFSET] - (u_char *)ip;
goto bad;
}
(void)memcpy(&ipaddr.sin_addr, sin,
sizeof(struct in_addr));
if (ifa_ifwithaddr((SA)&ipaddr) == NULL)
continue;
cp[IPOPT_OFFSET] += sizeof(struct in_addr);
off += sizeof(struct in_addr);
break;
default:
code = &cp[IPOPT_OFFSET + 1] - (u_char *)ip;
goto bad;
}
ntime = iptime();
(void)memcpy(cp + off, &ntime, sizeof(n_time));
cp[IPOPT_OFFSET] += sizeof(n_time);
}
}
if (forward && ipforwarding) {
ip_forward(m, 1);
return (1);
}
return (0);
bad:
icmp_error(m, type, code, 0, 0);
ipstat.ips_badoptions++;
return (1);
}
/*
* Given address of next destination (final or next hop),
* return internet address info of interface to be used to get there.
*/
struct in_ifaddr *
ip_rtaddr(dst)
struct in_addr dst;
{
struct route sro;
struct sockaddr_in *sin;
struct in_ifaddr *ifa;
bzero(&sro, sizeof(sro));
sin = (struct sockaddr_in *)&sro.ro_dst;
sin->sin_family = AF_INET;
sin->sin_len = sizeof(*sin);
sin->sin_addr = dst;
rtalloc_ign(&sro, RTF_CLONING);
if (sro.ro_rt == NULL)
return ((struct in_ifaddr *)0);
ifa = ifatoia(sro.ro_rt->rt_ifa);
RTFREE(sro.ro_rt);
return ifa;
}
/*
* Save incoming source route for use in replies,
* to be picked up later by ip_srcroute if the receiver is interested.
*/
static void
save_rte(option, dst)
u_char *option;
struct in_addr dst;
{
unsigned olen;
olen = option[IPOPT_OLEN];
#ifdef DIAGNOSTIC
if (ipprintfs)
printf("save_rte: olen %d\n", olen);
#endif
if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
return;
bcopy(option, ip_srcrt.srcopt, olen);
ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
ip_srcrt.dst = dst;
}
/*
* Retrieve incoming source route for use in replies,
* in the same form used by setsockopt.
* The first hop is placed before the options, will be removed later.
*/
struct mbuf *
ip_srcroute()
{
register struct in_addr *p, *q;
register struct mbuf *m;
if (ip_nhops == 0)
return ((struct mbuf *)0);
m = m_get(M_DONTWAIT, MT_HEADER);
if (m == NULL)
return ((struct mbuf *)0);
#define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
/* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
OPTSIZ;
#ifdef DIAGNOSTIC
if (ipprintfs)
printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
#endif
/*
* First save first hop for return route
*/
p = &ip_srcrt.route[ip_nhops - 1];
*(mtod(m, struct in_addr *)) = *p--;
#ifdef DIAGNOSTIC
if (ipprintfs)
printf(" hops %lx", (u_long)ntohl(mtod(m, struct in_addr *)->s_addr));
#endif
/*
* Copy option fields and padding (nop) to mbuf.
*/
ip_srcrt.nop = IPOPT_NOP;
ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
(void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr),
&ip_srcrt.nop, OPTSIZ);
q = (struct in_addr *)(mtod(m, caddr_t) +
sizeof(struct in_addr) + OPTSIZ);
#undef OPTSIZ
/*
* Record return path as an IP source route,
* reversing the path (pointers are now aligned).
*/
while (p >= ip_srcrt.route) {
#ifdef DIAGNOSTIC
if (ipprintfs)
printf(" %lx", (u_long)ntohl(q->s_addr));
#endif
*q++ = *p--;
}
/*
* Last hop goes to final destination.
*/
*q = ip_srcrt.dst;
#ifdef DIAGNOSTIC
if (ipprintfs)
printf(" %lx\n", (u_long)ntohl(q->s_addr));
#endif
return (m);
}
/*
* Strip out IP options, at higher
* level protocol in the kernel.
* Second argument is buffer to which options
* will be moved, and return value is their length.
* XXX should be deleted; last arg currently ignored.
*/
void
ip_stripoptions(m, mopt)
register struct mbuf *m;
struct mbuf *mopt;
{
register int i;
struct ip *ip = mtod(m, struct ip *);
register caddr_t opts;
int olen;
olen = (ip->ip_hl << 2) - sizeof (struct ip);
opts = (caddr_t)(ip + 1);
i = m->m_len - (sizeof (struct ip) + olen);
bcopy(opts + olen, opts, (unsigned)i);
m->m_len -= olen;
if (m->m_flags & M_PKTHDR)
m->m_pkthdr.len -= olen;
ip->ip_v = IPVERSION;
ip->ip_hl = sizeof(struct ip) >> 2;
}
u_char inetctlerrmap[PRC_NCMDS] = {
0, 0, 0, 0,
0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH,
EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED,
EMSGSIZE, EHOSTUNREACH, 0, 0,
0, 0, EHOSTUNREACH, 0,
ENOPROTOOPT, ECONNREFUSED
};
/*
* Forward a packet. If some error occurs return the sender
* an icmp packet. Note we can't always generate a meaningful
* icmp message because icmp doesn't have a large enough repertoire
* of codes and types.
*
* If not forwarding, just drop the packet. This could be confusing
* if ipforwarding was zero but some routing protocol was advancing
* us as a gateway to somewhere. However, we must let the routing
* protocol deal with that.
*
* The srcrt parameter indicates whether the packet is being forwarded
* via a source route.
*/
void
ip_forward(struct mbuf *m, int srcrt)
{
struct ip *ip = mtod(m, struct ip *);
struct in_ifaddr *ia = NULL;
int error, type = 0, code = 0;
struct mbuf *mcopy;
struct in_addr dest;
struct ifnet *destifp, dummyifp;
#ifdef DIAGNOSTIC
if (ipprintfs)
printf("forward: src %lx dst %lx ttl %x\n",
(u_long)ip->ip_src.s_addr, (u_long)ip->ip_dst.s_addr,
ip->ip_ttl);
#endif
if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(ip->ip_dst) == 0) {
ipstat.ips_cantforward++;
m_freem(m);
return;
}
#ifdef IPSTEALTH
if (!ipstealth) {
#endif
if (ip->ip_ttl <= IPTTLDEC) {
icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS,
0, 0);
return;
}
#ifdef IPSTEALTH
}
#endif
if (!srcrt && (ia = ip_rtaddr(ip->ip_dst)) == NULL) {
icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
return;
}
/*
* Save the IP header and at most 8 bytes of the payload,
* in case we need to generate an ICMP message to the src.
*
* XXX this can be optimized a lot by saving the data in a local
* buffer on the stack (72 bytes at most), and only allocating the
* mbuf if really necessary. The vast majority of the packets
* are forwarded without having to send an ICMP back (either
* because unnecessary, or because rate limited), so we are
* really we are wasting a lot of work here.
*
* We don't use m_copy() because it might return a reference
* to a shared cluster. Both this function and ip_output()
* assume exclusive access to the IP header in `m', so any
* data in a cluster may change before we reach icmp_error().
*/
MGET(mcopy, M_DONTWAIT, m->m_type);
if (mcopy != NULL && !m_dup_pkthdr(mcopy, m, M_DONTWAIT)) {
/*
* It's probably ok if the pkthdr dup fails (because
* the deep copy of the tag chain failed), but for now
* be conservative and just discard the copy since
* code below may some day want the tags.
*/
m_free(mcopy);
mcopy = NULL;
}
if (mcopy != NULL) {
mcopy->m_len = imin((ip->ip_hl << 2) + 8,
(int)ip->ip_len);
mcopy->m_pkthdr.len = mcopy->m_len;
m_copydata(m, 0, mcopy->m_len, mtod(mcopy, caddr_t));
}
#ifdef IPSTEALTH
if (!ipstealth) {
#endif
ip->ip_ttl -= IPTTLDEC;
#ifdef IPSTEALTH
}
#endif
/*
* If forwarding packet using same interface that it came in on,
* perhaps should send a redirect to sender to shortcut a hop.
* Only send redirect if source is sending directly to us,
* and if packet was not source routed (or has any options).
* Also, don't send redirect if forwarding using a default route
* or a route modified by a redirect.
*/
dest.s_addr = 0;
if (!srcrt && ipsendredirects && ia->ia_ifp == m->m_pkthdr.rcvif) {
struct sockaddr_in *sin;
struct route ro;
struct rtentry *rt;
bzero(&ro, sizeof(ro));
sin = (struct sockaddr_in *)&ro.ro_dst;
sin->sin_family = AF_INET;
sin->sin_len = sizeof(*sin);
sin->sin_addr = ip->ip_dst;
rtalloc_ign(&ro, RTF_CLONING);
rt = ro.ro_rt;
if (rt && (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
satosin(rt_key(rt))->sin_addr.s_addr != 0) {
#define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa))
u_long src = ntohl(ip->ip_src.s_addr);
if (RTA(rt) &&
(src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) {
if (rt->rt_flags & RTF_GATEWAY)
dest.s_addr = satosin(rt->rt_gateway)->sin_addr.s_addr;
else
dest.s_addr = ip->ip_dst.s_addr;
/* Router requirements says to only send host redirects */
type = ICMP_REDIRECT;
code = ICMP_REDIRECT_HOST;
#ifdef DIAGNOSTIC
if (ipprintfs)
printf("redirect (%d) to %lx\n", code, (u_long)dest.s_addr);
#endif
}
}
if (rt)
RTFREE(rt);
}
error = ip_output(m, (struct mbuf *)0, NULL, IP_FORWARDING, 0, NULL);
if (error)
ipstat.ips_cantforward++;
else {
ipstat.ips_forward++;
if (type)
ipstat.ips_redirectsent++;
else {
if (mcopy)
m_freem(mcopy);
return;
}
}
if (mcopy == NULL)
return;
destifp = NULL;
switch (error) {
case 0: /* forwarded, but need redirect */
/* type, code set above */
break;
case ENETUNREACH: /* shouldn't happen, checked above */
case EHOSTUNREACH:
case ENETDOWN:
case EHOSTDOWN:
default:
type = ICMP_UNREACH;
code = ICMP_UNREACH_HOST;
break;
case EMSGSIZE:
type = ICMP_UNREACH;
code = ICMP_UNREACH_NEEDFRAG;
#if defined(IPSEC) || defined(FAST_IPSEC)
/*
* If the packet is routed over IPsec tunnel, tell the
* originator the tunnel MTU.
* tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
* XXX quickhack!!!
*/
{
struct secpolicy *sp = NULL;
int ipsecerror;
int ipsechdr;
struct route *ro;
#ifdef IPSEC
sp = ipsec4_getpolicybyaddr(mcopy,
IPSEC_DIR_OUTBOUND,
IP_FORWARDING,
&ipsecerror);
#else /* FAST_IPSEC */
sp = ipsec_getpolicybyaddr(mcopy,
IPSEC_DIR_OUTBOUND,
IP_FORWARDING,
&ipsecerror);
#endif
if (sp != NULL) {
/* count IPsec header size */
ipsechdr = ipsec4_hdrsiz(mcopy,
IPSEC_DIR_OUTBOUND,
NULL);
/*
* find the correct route for outer IPv4
* header, compute tunnel MTU.
*
* XXX BUG ALERT
* The "dummyifp" code relies upon the fact
* that icmp_error() touches only ifp->if_mtu.
*/
/*XXX*/
destifp = NULL;
if (sp->req != NULL
&& sp->req->sav != NULL
&& sp->req->sav->sah != NULL) {
ro = &sp->req->sav->sah->sa_route;
if (ro->ro_rt && ro->ro_rt->rt_ifp) {
dummyifp.if_mtu =
ro->ro_rt->rt_rmx.rmx_mtu ?
ro->ro_rt->rt_rmx.rmx_mtu :
ro->ro_rt->rt_ifp->if_mtu;
dummyifp.if_mtu -= ipsechdr;
destifp = &dummyifp;
}
}
#ifdef IPSEC
key_freesp(sp);
#else /* FAST_IPSEC */
KEY_FREESP(&sp);
#endif
ipstat.ips_cantfrag++;
break;
} else
#endif /*IPSEC || FAST_IPSEC*/
/*
* When doing source routing 'ia' can be NULL. Fall back
* to the minimum guaranteed routeable packet size and use
* the same hack as IPSEC to setup a dummyifp for icmp.
*/
if (ia == NULL) {
dummyifp.if_mtu = IP_MSS;
destifp = &dummyifp;
} else
destifp = ia->ia_ifp;
#if defined(IPSEC) || defined(FAST_IPSEC)
}
#endif /*IPSEC || FAST_IPSEC*/
ipstat.ips_cantfrag++;
break;
case ENOBUFS:
/*
* A router should not generate ICMP_SOURCEQUENCH as
* required in RFC1812 Requirements for IP Version 4 Routers.
* Source quench could be a big problem under DoS attacks,
* or if the underlying interface is rate-limited.
* Those who need source quench packets may re-enable them
* via the net.inet.ip.sendsourcequench sysctl.
*/
if (ip_sendsourcequench == 0) {
m_freem(mcopy);
return;
} else {
type = ICMP_SOURCEQUENCH;
code = 0;
}
break;
case EACCES: /* ipfw denied packet */
m_freem(mcopy);
return;
}
icmp_error(mcopy, type, code, dest.s_addr, destifp);
}
void
ip_savecontrol(inp, mp, ip, m)
register struct inpcb *inp;
register struct mbuf **mp;
register struct ip *ip;
register struct mbuf *m;
{
if (inp->inp_socket->so_options & (SO_BINTIME | SO_TIMESTAMP)) {
struct bintime bt;
bintime(&bt);
if (inp->inp_socket->so_options & SO_BINTIME) {
*mp = sbcreatecontrol((caddr_t) &bt, sizeof(bt),
SCM_BINTIME, SOL_SOCKET);
if (*mp)
mp = &(*mp)->m_next;
}
if (inp->inp_socket->so_options & SO_TIMESTAMP) {
struct timeval tv;
bintime2timeval(&bt, &tv);
*mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
SCM_TIMESTAMP, SOL_SOCKET);
if (*mp)
mp = &(*mp)->m_next;
}
}
if (inp->inp_flags & INP_RECVDSTADDR) {
*mp = sbcreatecontrol((caddr_t) &ip->ip_dst,
sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
if (*mp)
mp = &(*mp)->m_next;
}
if (inp->inp_flags & INP_RECVTTL) {
*mp = sbcreatecontrol((caddr_t) &ip->ip_ttl,
sizeof(u_char), IP_RECVTTL, IPPROTO_IP);
if (*mp)
mp = &(*mp)->m_next;
}
#ifdef notyet
/* XXX
* Moving these out of udp_input() made them even more broken
* than they already were.
*/
/* options were tossed already */
if (inp->inp_flags & INP_RECVOPTS) {
*mp = sbcreatecontrol((caddr_t) opts_deleted_above,
sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
if (*mp)
mp = &(*mp)->m_next;
}
/* ip_srcroute doesn't do what we want here, need to fix */
if (inp->inp_flags & INP_RECVRETOPTS) {
*mp = sbcreatecontrol((caddr_t) ip_srcroute(),
sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
if (*mp)
mp = &(*mp)->m_next;
}
#endif
if (inp->inp_flags & INP_RECVIF) {
struct ifnet *ifp;
struct sdlbuf {
struct sockaddr_dl sdl;
u_char pad[32];
} sdlbuf;
struct sockaddr_dl *sdp;
struct sockaddr_dl *sdl2 = &sdlbuf.sdl;
if (((ifp = m->m_pkthdr.rcvif))
&& ( ifp->if_index && (ifp->if_index <= if_index))) {
sdp = (struct sockaddr_dl *)
(ifaddr_byindex(ifp->if_index)->ifa_addr);
/*
* Change our mind and don't try copy.
*/
if ((sdp->sdl_family != AF_LINK)
|| (sdp->sdl_len > sizeof(sdlbuf))) {
goto makedummy;
}
bcopy(sdp, sdl2, sdp->sdl_len);
} else {
makedummy:
sdl2->sdl_len
= offsetof(struct sockaddr_dl, sdl_data[0]);
sdl2->sdl_family = AF_LINK;
sdl2->sdl_index = 0;
sdl2->sdl_nlen = sdl2->sdl_alen = sdl2->sdl_slen = 0;
}
*mp = sbcreatecontrol((caddr_t) sdl2, sdl2->sdl_len,
IP_RECVIF, IPPROTO_IP);
if (*mp)
mp = &(*mp)->m_next;
}
}
/*
* XXX these routines are called from the upper part of the kernel.
* They need to be locked when we remove Giant.
*
* They could also be moved to ip_mroute.c, since all the RSVP
* handling is done there already.
*/
static int ip_rsvp_on;
struct socket *ip_rsvpd;
int
ip_rsvp_init(struct socket *so)
{
if (so->so_type != SOCK_RAW ||
so->so_proto->pr_protocol != IPPROTO_RSVP)
return EOPNOTSUPP;
if (ip_rsvpd != NULL)
return EADDRINUSE;
ip_rsvpd = so;
/*
* This may seem silly, but we need to be sure we don't over-increment
* the RSVP counter, in case something slips up.
*/
if (!ip_rsvp_on) {
ip_rsvp_on = 1;
rsvp_on++;
}
return 0;
}
int
ip_rsvp_done(void)
{
ip_rsvpd = NULL;
/*
* This may seem silly, but we need to be sure we don't over-decrement
* the RSVP counter, in case something slips up.
*/
if (ip_rsvp_on) {
ip_rsvp_on = 0;
rsvp_on--;
}
return 0;
}
void
rsvp_input(struct mbuf *m, int off) /* XXX must fixup manually */
{
if (rsvp_input_p) { /* call the real one if loaded */
rsvp_input_p(m, off);
return;
}
/* Can still get packets with rsvp_on = 0 if there is a local member
* of the group to which the RSVP packet is addressed. But in this
* case we want to throw the packet away.
*/
if (!rsvp_on) {
m_freem(m);
return;
}
if (ip_rsvpd != NULL) {
rip_input(m, off);
return;
}
/* Drop the packet */
m_freem(m);
}
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